Received: 11 March 2017 | Revised: 1 August 2017 | Accepted: 11 August 2017 DOI: 10.1002/ece3.3579

ORIGINAL RESEARCH

An integrative mating system assessment of a nonmodel, economically important Pacific rockfish (Sebastes melanops) reveals nonterritorial polygamy and conservation implications for a large species flock

Kurt W. Karageorge | Raymond R. Wilson Jr.

Department of Biological Sciences, California State University, Long Beach, CA, USA Abstract Characterizing the mating systems of long-­lived, economically important Pacific rock- Correspondence Kurt W. Karageorge, Washington Department fishes comprising the viviparous Sebastes species flock is crucial for their conservation. of Fish & Wildlife, 16018 Mill Creek Blvd., Mill However, direct assignment of mating success to sires is precluded by open, offshore Creek, WA 98012-1541. Email: [email protected]. populations and high female fecundity. We addressed this challenge by integrating edu paternity-­assigned mating success of females with the adult sex ratio (ASR) of the pop-

Funding information ulation, male evolutionary responses to receptive females, and reproductive life history Southern California Academy of Sciences traits—in the framework of sexual selection theory—to assess the mating system of Student Grant Program; SCTC Marine Biology Educational Foundation; Richard B. Loomis Sebastes melanops. Microsatellite parentage analysis of 17 pregnant females, 1,256 of Foundation at California State University, their progeny, and 106 adults from the population yielded one to four sires per brood, Long Beach a mean of two sires, and a female mate frequency distribution with a truncated normal (random) pattern. The 11 multiple paternity broods all contained higher median­ allele richness than the six single paternity broods (Wilcoxon test: W = 0, p < .001), despite similar levels of average heterozygosity. By sampling sperm and alleles from different males, polyandrous females gain opportunities to enhance their sperm supply and to lower the cost of mating with genetically incompatible males through reproductive compensation. A mean of two mates per mated female with a variance of one, an ASR = 1.2 females per male, and the expected population mean of 2.4 mates for mated males (and the estimated 35 unavailable sires), fits polygamous male mate frequency distributions that distinguish polygynandry and polyandrogyny mating systems, that is, variations of polygamy, but not polyandry. Inference for polygamy is consistent with weak premating sexual selection on males, expected in mid-­water, schooling S. melan- ops, owing to polyandrous mating, moderately aggregated receptive females, an even ASR, and no territories and nests used for reproduction. Each of these characteristics facilitates more mating males and erodes conspicuous sexual ­dimorphism. Evaluation of male evolutionary responses of demersal congeners that express reproductively ter- ritorial behavior revealed they have more potential mechanisms for producing premat- ing sexual selection, greater variation in reproductive success, and a reduced breeding effective population size of adults and annual effective size of a cohort, compared to

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 www.ecolevol.org | 11277 Ecology and Evolution. 2017;7:11277–11291. 11278 | KARAGEORGE and WILSON Jr

S. melanops modeled with two mates per adult. Such divergence in behavior and mating system by territorial species may ­differentially lower their per capita birth rates, subse- quent population growth, and slow their ­recovery from exploitation.

KEYWORDS genetic incompatibility, polyandrogyny, polyandrous females, polygynandry, premating, sexual selection, Viviparity-Driven Conflict Hypothesis

1 | INTRODUCTION abundance, despite over two decades of potential recovery with de- clining fishing mortality (Hutchings & Reynolds, 2004). At low popula- 1.1 | The importance of understanding mating tion sizes, the per capita population growth rate, r, may decline due to systems demographic stochasticity and positive density dependence (i.e., Allee effects; Møller & Legendre, 2001), and disrupt normal mating system Mating systems fundamentally impact the ecology, evolution, and function. Delays in the optimal timing of reproduction, a reduced in- extinction of populations, and require our scientific inquiry for con- tensity of social interactions, skewed sex ratios, and reduced/skewed servation. A mating system embodies the relationships among repro- mating and fertilization success can lower birth rates and N below an ductively receptive individuals, their offspring, and the environment e already low census size (Anthony & Blumstein, 2000; Parker & Waite, over the reproductive season (Emlen & Oring, 1977), and can gen- 1997; Rowe & Hutchings, 2003). Moreover, intense sexual selection erate sexual selection from competition for fertilization, that occurs within some mating systems can weaken the recovery of small popu- directly between members of the same sex (e.g., male–male competi- lations (Blumstein, 1998; Møller, 2000; Møller & Legendre, 2001). tion and sperm competition), or indirectly, between the attraction of Pacific rockfishes of the viviparous genus Sebastes are a unique one sex to the other (e.g., female choice; Andersson, 1994; Darwin, component of biodiversity because they encompass the criteria that 1871). Premating competition mechanisms create variation in mat- define a species flock (Johns & Avise, 1998). Explosive speciation of ing success among individuals that, in combination with any postmat- the genus Sebastes has generated over 100 species that have adapted ing competition, results in variation in their reproductive success and throughout most of their endemic range. Sebastes species occur in pe- sexual selection (Bateman, 1948; Jones, Arguello, & Arnold, 2002; lagic and demersal environments along the continental shelf, slope, Wade, 1979; Warner, Shapiro, Marcanato, & Petersen, 1995), princi- and seamounts of the North Pacific Ocean—in contrast to sister gen- pally when more adults of one sex do not mate (sensu Darwin, 1871; era (e.g., Hozukius, Sebastiscus, etc.; Kendall, 2000). Yet, populations of Shuster, 2009). Consequential to conservation, mating systems with many rockfish species are overfished remnants of their former large strong directional sexual selection and reproductive exclusion, and/ sizes, while we lack a mating system assessment for any of the es- or with sexual conflict (different reproductive interests of males and timated 70 Sebastes species in the northeastern Pacific. A barrier to females), experience an associated reduction in effective population mating system studies in nature arises from the difficulty of obtain- size, N (Holland & Rice, 1999; Nunney, 1993; Parker & Waite, 1997; e ing the means and variances of mating and reproductive success for Warner et al., 1995). Reproductive behavior also affects many bio- a breeding population, especially for nonmodel marine organisms, like logical processes that differentially impact N (Anthony & Blumstein, e Pacific rockfishes. Large, open populations coupled with high fecun- 2000; Baer & Schmid-­Hempel, 1999; Darden & Croft, 2008; Hoglund, dity prohibits direct assignment of mating success to the nonpregnant 1996), including inbreeding (Meagher, Penn, & Potts, 2000) and off- sex (or the nonbrood guarding sex), that is, unavailable parents—mated spring viability (Newcomer, Zeh, & Zeh, 1999). Ultimately, mating males/sires for Sebastes species—because a candidate pool of sires systems and sexual selection may promote the evolution of popu- cannot be identified (Jones & Ardren, 2003). Fortunately, integrating lations through reproductive isolation and speciation (reviewed in paternity estimates of female mating success with the population con- Panhuis, Butlin, Zuk, & Tregenza, 2001), or increase their extinction straint of the adult sex ratio, and the evolutionary responses of males risk (Møller, 2000; Møller & Legendre, 2001). Accordingly, the as- to receptive females in the framework of sexual selection theory—can sessment of a species’ mating system is a vital step for conservation help diagnose mating systems of Sebastes species. (Parker & Waite, 1997; Vincent & Sadovy, 1998) and is the purpose Since Darwin’s (1871) formulation of sexual selection theory, of this study. it has been evident that the expression of secondary sex traits depends on the mating system (including parental roles), and that strong reciprocal relationships between mating systems and their 1.2 | Mating systems and the conservation of strength and direction of sexual selection exist (Andersson, 1994; commercially exploited fish Arnold, 1994; Bateman, 1948; Jones & Avise, 2001). Darwin (1871) The severe reduction in many commercially exploited marine fish described species with intense polygyny (males with highly vari- populations has resulted in little to no increase in their postcollapse able mating success, relative to monandrous females) possessing KARAGEORGE and WILSON Jr | 11279

“strongly marked” sexual differences, but less so in moderately po- lygynous animals, and little dimorphism in monogamous species. Contemporary evidence for sexual dimorphism as an evolutionary response to the intensity of premating sexual selection comes from microsatellite-­based studies of genetic mating systems. Polyandry, referred to in this study as a population-­level mating system where females are variable in their mating success, whereas each male has at most one mate, was discovered in the strongly sexually dimorphic pipefish Syngnathus scovelli (Jones, Walker, & Avise, 2001). Slight, transient sexual dimorphism is expressed by S. typhle, where po- lygynandry, a form of polygamy, was appraised (Jones, Rosenqvist, Berglund, & Avise, 1999). An intriguing feature of Sebastes species is the striking, inconspicuous sexual dimorphism between the sexes (Lenarz & Wyllie Echeverria, 1991; Love, Morris, McCrae, & Collins, FIGURE 1 A school of adult Sebastes melanops, over a shallow 1990; Wyllie Echeverria, 1986), which lack sexually selected second- water temperate rocky reef near the Redfish Rocks Marine Protected ary sex characters such as male weaponry, strong sexual size dimor- Area off the coast of southern Oregon, USA. Photo courtesy of Oregon Department of Fish and Wildlife phism, body patterning, and male nuptial colorations. Also absent are secondary sex traits associated with the environment that are not used in rockfish reproduction: nests for all Sebastes species (be- 2 | MATERIALS AND METHODS cause they are viviparous), and courtship/mating territories by the mid-­water, schooling species that are reproductively nonterritorial. 2.1 | Sample collection In situ observations convey that the most prominent male secondary sex trait is a transient, behavioral visual signal: courtship displays, ei- We sampled the recreational fishery landings for S. melanops adults ther in the water column, or on territories (Helvey, 1982; Shinomiya caught at nearshore rocky reefs (<30 m) off Newport, Oregon, U.S.A. & Ezaki, 1991). We posit that if multiple paternity is documented in During January through March (2004), the season of S. melanops fer- a Sebastes species (Van Doornik, Parker, Millard, Berntson, & Moran, tilization and embryonic development (Bobko & Berkeley, 2004), we 2008; Hyde et al., 2008; Sogard et al., 2008), with schooling, non- surveyed adults for gravid females and females with whole-­brood ab- territorial behavior as adults, a likely genetic mating system would sorption of ova, which could indicate the occurrence of unmated adult be a form of polygamy, as monogamy and polygyny are disqualified. females. Due to the high fecundity of female broods, the number of Polyandry is also possible, but Sebastes species do not show sex-­ offspring per brood was randomly sampled, and the minimum desired role reversal characteristics in behavior or morphology (reviewed sample size was chosen to detect sires that might fertilize a small frac- in Gwynne, 1991): females do not appear to compete for males tion of ova. Binomial power analysis indicated that 58 offspring per (Helvey, 1982; Shinomiya & Ezaki, 1991), and no elaborated second- brood were needed to detect at least one paternal allele/offspring ary sex traits are evident among females. from a father that sired only 5% of a brood, with a 0.95 probability We assess the mating system of S. melanops (Figure 1), using an (sensu Bartley, Kent, & Drawbridge, 1995; see Sokal & Rohlf, 1995 for integrative framework. Adults in the breeding population and off- binomial power analysis). To account for some offspring that would spring from pregnant females are used to estimate the mating suc- fail to amplify, for example, due to small tissue samples, degraded cess of mothers and indirectly estimate the average mating success DNA, and Chelex resin occasionally in the PCR, we sampled 96 off- of the unavailable mated males. These mating system measures spring per brood to fill 96-­well DNA extraction plates. are then used to evaluate a male mate frequency distribution cor- During September through November (2007), the mating season responding to a (expected) null mating system hypothesis of poly- of S. melanops (Wyllie Echeverria, 1987), we sampled adults from andry, against the alternative hypothesis of polygamy. Inference on the population to estimate the adult sex ratio, so that the population the mating system of S. melanops is also supported by comparing demographic inference on the average number of mates of mated the evolutionary responses of males to receptive females between males could be drawn. We also collected DNA tissue from adults to Sebastes species comprising two major life history groups and by assess their genetic variation and to calculate the combined exclu- assessing the expected strength of premating sexual selection on sionary probability of various locus combinations to discriminate a males. We also examine the effect of female mating strategies on the random male in the population as being the sire of a brood (Jones, genetic diversity of broods and their implications for female fitness. 2005). Sebastes melanops that measured at least 360 mm total length, Lastly, we model the effect of the supported S. melanops mating sys- the length at 50% population maturity for males (which experience tem on the relationship between annual effective population size a smaller size at maturity than females; Wyllie Echeverria, 1987), and reproductive failure and show how divergence of behavior and were further examined for sex and maturity based on the external mating system of congeners with an alternate life history could alter morphology of ovaries and testes (Gunderson, Callahan, & Goiney, this relationship. 1980). Binomial power analysis indicated that 74 adult S. melanops 11280 | KARAGEORGE and WILSON Jr were needed for a 0.95 probability of encountering rare alleles with a combination of paternal genotypes for a given number of sires was relative frequency ≥0.02 in the adult population (Bartley et al., 1995; reconstructed, then the most likely paternal genotypic combination Sokal & Rohlf, 1995). Maternal fin clips, whole ovaries with offspring, was accepted. We estimated the relative paternity share for each and adult fin clips were isolated and preserved in the field with 95% sire within all multiple sired broods, based on the number of prog- ethanol and then stored at 4°C. eny assigned to each sire (i.e., reconstructed paternal genotype), but we tested for significant paternity skew only in broods with one paternal solution; that is, genotypic combination of sires. We used 2.2 | Preparentage analysis: DNA extraction, PCR, GERUDsim2.0 (Jones, 2005) to test the accuracy of GERUD2.0 to genotyping, locus performance and population genetic correctly determine the true number of sires of each progeny array, analysis with selected loci employing the number of offspring assigned to each sire and the adult We tested congeneric microsatellite loci on the adult population sam- population allele frequencies. ple to assess their amplification quality, level of polymorphism, allele We estimated the harmonic mean number of mates of mated fe- frequencies, heterozygosities, and agreement of genotype frequen- males, which equals the average of the inverse of the number of mates cies to Hardy–Weinberg proportions (HWP) for parentage analysis. per female, from the paternity results over all 17 females. It represents Genomic DNA was extracted using a standard 5% Chelex digestion the fraction of an average female’s brood that an average male is ex- (Wilson & Donaldson, 1998), and loci were amplified in each 6-μ­ l PCR pected to sire (i.e., population average paternity share per male), and in- that included a final concentration of 1× Taq buffer, 1–2 mmol/L MgCl2, dicates the possible intensity of sperm competition among mated males, 0.07–0.10 μmol/L of each forward and reverse primer, 0.2 mmol/L of under a model of sperm mixing and equal paternity by all inseminating each DNTP, 0.1 U Taq polymerase, and 25–100 ng of template DNA. males, when females mate at least once, and each male mates with a par- PCR conditions for S. melanops were as described by Miller, Schulze, ticular female only once (Shuster & Wade, 2003; Wade & Arnold, 1980). and Withler (2000) for Sal1 and Sal3 loci, developed from Pacific Ocean perch, S. alutus (GenBank Accession numbers AF153595 and 2.4 | Effect of female mating strategy on the genetic AF153597, respectively); and by Gomez-­Uchida, Hoffman, Ardren, diversity of broods and Banks (2003) for the Spi6 locus, developed from canary rockfish, S. pinniger (GenBank no. AY192600). However, we optimized anneal- We compared the genetic diversity, as average observed heterozy- ing temperatures at 46°C for Sal1 and 58°C for Sal3. PCR products gosity and median allele richness, between broods that were sired by were resolved on a LI-­COR 4300 DNA Analyzer and scored with the multiple males and broods that were sired by a single male. We also Saga 2 Microsatellite Analysis Program (LI-­COR, Lincoln, Nebraska, tested for a significant difference in the observed heterozygosity be- U.S.A.). We selected Sal1, Sal3, and Spi6 loci to genotype S. melanops tween all pooled offspring and the adult population sample. Statistical mothers and their progeny. These loci displayed little nonspecific am- tests and graphics were produced with the statistical program R (R plification relative to other polymorphic loci we tested on the adult Core Development Team, 2016; http:/www.r-project.org). population sample, yielded 11 to 18 alleles per locus, and produced a multilocus exclusion probability of 0.977. Genotypes were analyzed 2.5 | Population demographic inference on the with ARLEQUIN version 3.5 (Excoffier & Lischer, 2010). The geno- average mate frequency of the unavailable parents: type frequencies of the adult population sample did not deviate from mated males HWP (Sal1: Ho = 0.86, He = 0.90, p = 0.59; Sal3: Ho = 0.90, He = 0.85, p = 0.30; Spi6: Ho = 0.84, He = 0.82, p = 0.17), nor show significant Predicting the average number of mates for mated males in a popula- linkage disequilibrium between loci (Sal1/Sal3, p = 0.06; Sal1/Spi6, tion is possible, even when paternity assignment of progeny and all p = 0.11; Sal3/Spi6, p = .06). Additional steps taken to minimize scor- mates to individual males is not possible, because the total ­number of ing error included amplifying all samples at least twice (in separate mates that bear progeny with females must equal the total ­number of PCR sessions) to compare scoring consistency between replicates. mates of males (Fisher, 1958). Consequently, the average number We also verified the inheritance of maternal alleles in progeny against of mates per male and female is joined through the sex ratio (Arnold the genotype of their known mother and tested maternal allele fre- & Duvall, 1994; Shuster & Wade, 2003), that we estimated as the quencies in each progeny array for departures from an expected 1:1 ratio of the number of adult females to the number of adult males: Mendelian segregation ratio. ASR = n /n . We estimated the average number of mates mature ♀ mature ♂ x̄∗ of mated females in the breeding population, f (and the variance, v∗), from the number of reconstructed sires of brooded females, so 2.3 | Paternity analysis and inference on female f that the average number of mates per mated male, a key mating sys- mate numbers x̄∗ = (ASR)x̄∗ tem parameter, could be estimated with the equation: m f Paternity analysis of each S. melanops brood was accomplished by (Shuster & Wade, 2003). The parameter estimates draw inference reconstructing the minimum number of sires that could explain the on mated individuals and do not include unmated adults. We assume three-­locus progeny array sample with known mother, using the that the unknown proportions of unmated adult males and females computer program GERUD2.0 (Jones, 2005). When more than one within the ASR are similar (i.e., similar sizes of the zero mate frequency KARAGEORGE and WILSON Jr | 11281 classes). Potential violations of this assumption and biases of param- evolutionary responses separately for congeners that exhibit solitary eter estimates are also evaluated. The expected strength of premating behavior or form loose aggregations as adults, typically occur on or sexual selection on males, an indicator of the magnitude of unmated near the substrata (Love et al., 1990; “demersal state”, Kendall, 2000), males, is addressed below. To assess which male mate frequency dis- and are confirmed to be reproductively territorial (Shinomiya & Ezaki, tributions and corresponding (genetic) mating systems were consist- 1991), or expected to be (Gingras, Ventresca, Donnellan, & Fisher, ent with S. melanops, we compared the observed mean and variance 1998) due to strong territorial behavior for feeding and shelter areas x̄∗, v∗ of the number of mates of mated females ( f f), the ASR, and the (Larson, 1980a,b), and long-­term site fidelity (R. Larson, pers. comm.). x̄∗ expected average number of mates of mated males ( m), against the Differences in the evolutionary responses of males between the two means and variances of male mate frequency distributions that char- life history groups were compared in the context of mating system acterize the following mating systems. Polyandry (Ho), when strong and sexual selection theory, for their potential influences on shaping premating directional sexual selection on females is likely (and strong the mating system and associated effective population size. sexual dimorphism is elaborated in females), resulting in females that are much more variable in their mating success than males, producing 2.7 | The influence of male and female reproductive a much larger zero mate frequency class of unmated females than the life history and ecology on shaping the sex difference zero class of unmated males (if present). Polyandrogyny (H ), when a in opportunity for selection weak directional sexual selection on females is expected (and weak sexual dimorphism may be inconspicuous), resulting in females that We also evaluated the underlying influences of male and female re- are somewhat more variable in their mating success than males, pro- productive life history and ecology on shaping the expected sex differ- ducing a larger zero class of unmated females than the zero class of ence in opportunity for selection, or opportunity for sexual selection, unmated males. Polygynandry (Ha), when weak directional sexual se- which indicates the overall expected strength of premating directional lection on males is expected (and weak sexual dimorphism may be sexual selection on males of S. melanops and congeners with a school- inconspicuous), resulting in males that are somewhat more variable ing, nonterritorial life history (and also for congeners with a demersal, in their mating success (and a larger zero class of unmated males than territorial life history). These evaluations provide theoretical support the zero class of unmated females; Shuster & Wade, 2003). for some of the observed and expected/apparent types of evolution- ary responses of males to female receptivity, and inference on the mating ­system (Appendix S1). 2.6 | Evaluation of the evolutionary responses of males to female spatiotemporal distributions in receptivity for S. melanops and other congeners in the 2.8 | The influence of the mating system on the large marine species flock relationship between annual effective population size and reproductive failure To further assess the mating system of S. melanops and predict other possible mating systems of Sebastes species for conservation, we We modeled the influence of different mating systems for their pre- followed the mating system classification framework of Shuster and dicted effects on the relationship between the annual effective popu-

Wade (2003), in combination with a comparative approach to identify lation size, Ne (i.e., within-­season and nonoverlapping generations, or suites of behaviors and characters that could produce—or be the re- a cohort), and the proportion of breeding adults/whole broods that sult of—different sexual selection mechanisms, and hence mating sys- experience reproductive failure, modifying the approach of Parker and tems, and that could facilitate appropriate management plans (Harvey Waite (1997). We applied different demographic variables and repro-

& Pagel, 1991; Vincent & Sadovy, 1998) for this large species flock. ductive failure assumptions to Wright’s (1931) equation Ne = (4nm*nf)/

Emlen and Oring (1977) showed that the spatiotemporal distributions (nm + nf), where nm and nf are the number of breeding males and fe- of receptive females affects the distribution of mating success among males. We defined the breeding sex ratio (BSR) as the ratio of adults males, yet the distribution of paternity is modified by the ability of that successfully mate, relative to the initial adult population size males to (1) engage in sperm competition, (2) search for or guard fe- of N = 100 adults, with 50 adults per sex (= ASR =1); the number of males and/or territories, (3) provide care of offspring, (4) cooperate mates per individual; and the effects of reproductive failure on Ne of with or exploit their mates (i.e., sexual conflict), or to (5) change mating a cohort, for each mating system, as follows. For polygamy (polyan- strategy (Shuster & Wade, 2003). We evaluated these evolutionary re- drogyny and polygynandry), the BSR = ASR = 1; no adults were ex- sponses of males to female receptivity for S. melanops, by integrating cluded from mating. The number of mates per adult is 2, the paternity our mating system parameter estimates with previous observations share of all broods = 0.5, and for each female’s unsuccessful brood

(elucidated by a comprehensive literature search) on the reproduc- (e.g., due to male sterility or postzygotic brood failure), nf is reduced tive behavior and biology of S. melanops and congeners with a similar by one, whereas that sire’s progeny/alleles are still represented in adult life history and ecology, characteristic of conspecific schooling another female’s brood; therefore, nm is reduced by one for every behavior as adults, occurrence in mid-­water above substrata (Love two females that experience reproductive failure. For monogamy, et al., 1990; “pelagic state”, Kendall, 2000), and are confirmed and/or the BSR = ASR = 1 and for every brood failure, all of a mating pair’s presumed to be reproductively nonterritorial. We then evaluated male progeny are eliminated from the cohort of the next generation. For 11282 | KARAGEORGE and WILSON Jr moderate polygyny, the BSR = 1♂:2♀, where 50% of the adult males Skewed paternity was unambiguously revealed in four broods, are excluded from mating by sexual selection, and the other 50% of where two sires and one paternal genotype solution were recon- males have two mates each, completely siring each of their mates’ structed. In each of these broods, one male sired a significant majority broods. The progeny of one male are eliminated from the cohort for of the sampled progeny (Ho = equal paternity between males, chi-­ every two brood failures. Polyandry was modeled in a similar manner: square tests: χ2 > 13.8, df = 1, p < 0.001 for each of the four broods; 50% of adult females have no mates (BSR = 2♂:1♀) and 50% mate with Figure 3a). The most extreme case of skewed paternity occurred in a two males each. Here the relative paternity share of all broods = 0.5, brood where 68 of the 71 genotyped progeny (96%) most likely had and every reproductive failure eliminates progeny from three parents the same father. In broods sired by three and four males, the relative (each male has one mate). Greater premating sexual selection was paternity share was more equitable among most of the sires, based on modeled by extreme polygyny, where only 10% of the males mate, the most likely paternal genotype solution (Figure 3b). Yet the relative each with 10% of the females, to the exclusion of other males. paternity share of these broods were less certain, due to more than

3 | RESULTS (a)

n = 74 (1)41 (4)67 (1) 72 (1) 82 (1) 71 (6) 3.1 | Paternity analysis and inference on female 1.0 mate numbers 0.96

Each Male 0.90

by 0.8 Paternity analysis of the 17 brooding mothers revealed that a mini- 0.76 mum of 52 parents (17 mothers and an estimated 35 sires) produced 0.72 0.73 0.74 0.6 the 1,256 genotyped offspring. The effective number of males siring a brood varied from one to four sires, and 65% of the broods were sired ing Sired 0.4 by two or more males, the population frequency of multiple paternity (Figure 2). Simulations on each progeny array indicated that we cor- 0.2 rectly identified the true number of sires fertilizing each brood with a ion of Offspr minimum probability of 0.95, that was lowest for the two broods sired by four males (Figure 2; see Table S1 for specific broods). Maternal 0.0 alleles were inherited by progeny in the expected 1:1 Mendelian ratio Propo rt 123456 for equal segregation, in 49 of the 51 locus-­by-­brood groups (i.e., 3 Brood loci × 17 broods = 51 groups/tests; Table S1). The probability of two (b) or fewer “false positives” of 51 tests is 0.52. n = 74 (3)80 (>50) 70 (10) 93 (12) 96 (3) 1.0 7 % of iterations correctly identifying all sires: Each Male 0.8

100 99 by 6 0.67 0.6 5 0.58 ing Sired 0.48 4 0.4 0.45 > 98 0.34 3 95−96 0.2 2 tion of Offspr

Number of broods 1 0.0 Propor 7891011 0 Brood 12345 FIGURE 3 Relative paternity share of sires within multiple sired Number of sires broods (i.e., females with two, three, or four subclutches, each with a different sire). The estimated proportion of offspring sired by the FIGURE 2 Microsatellite parentage analysis results of 17 field-­ male with the largest paternity share for each brood is indicated collected broods of Sebastes melanops. Female multiple mating is within each bar. Above the bars are the number of offspring common in this population, with 65% of the broods sired by two or genotyped, followed by the number of possible paternal genotypic more males. Above each bar (mate frequency class) is the percent of solutions for the number of sires detected, in parentheses. (a) relative simulation iterations that matched the number of reconstructed sires paternity share within broods sired by two males; (b) relative determined by the parentage program, using the number of offspring paternity share within broods sired by three and four males (showing per sire per brood and the population allele frequencies the most likely relative paternity share) KARAGEORGE and WILSON Jr | 11283 one paternal genotype solution for each brood. This resulted in differ- strategies/phenotypes (due in part to female control of copulation), ent proportions of progeny assigned to the three or four reconstructed and other evolutionary responses of males to female spatiotemporal sires of those broods. The estimated harmonic mean number of mates distributions in receptivity were consistent with moderate levels of of mated females in the population was 0.62. male mating success and weak directional sexual selection on males. These support a nonterritorial polygamy mating system classification for S. melanops (Table 1; Appendix S1). However, several reciprocal 3.2 | Effect of female mating strategy on the genetic evolutionary responses in the reproductive behavior, phenotypes, diversity of broods and ecology between Sebastes species that exhibit schooling, nonter- Polyandrous mating did not have a statistically significant effect on the ritorial behavior (NT) as adults, compared to congeners that express average observed heterozygosity of multiple sired broods, relative to occasional solitary, and demersal, territorial behavior (TT) as adults, monandrous mating and (effectively) single sired broods: the cumulative probability distributions of average observed heterozygosity of multiple paternity broods (820 progeny from 11 broods) and single paternity 1.0 (a) broods (432 progeny from six broods) were similar (Kolmogorov– y adult population: n = 106 Smirnov two-sample test statistic = 31, p > 0.10; Figure 4a). However, 0.9 multiple paternity broods were greater in median allele richness than single paternity broods (Wilcoxon test: W = 0, p < 0.001; Figure 4b). 0.8 The total offspring sample from multiple paternity broods carried an all offspring: n = 1256 average of about three more distinct alleles per locus than the total off- heterozygosit s. spring sample from single paternity broods. The observed heterozygo- 0.7 sity between all pooled offspring and the adult population sample was multiple paternity brood 2 not statistically different at any locus (Sal1: χ = 0.05, df = 1, p > 0.82; single paternity brood Mean ob 2 2 Sal3: χ = 2.30, df = 1, p > 0.13; Spi6: χ = 0.81, df = 1, p = 0.37). 0.6

3.3 | Population demographic inference on the 1357911131517 average mate frequency of mated males

x̄∗ = 2.0 6 (b) The mean number of mates of the gestating females was f , v∗ = 1.0 nmp b = 75 offspring with variance f . Our survey of hundreds of adult females for un- fertilized, atrophied broods, which could be the result of mating fail- ure, yielded only one potential case. The adult sex ratio sample was 5 ASR = 1.2, yielding a predicted mean number of mates per mated male all broods x̄∗ = = of m (2.0)(1.2) 2.4. The observed mean and variance of mated fe- x̄∗ 4 males, the ASR, and the predicted m (Figure 5a) were inconsistent with a mean and variance of males with a mate frequency distribution char- acteristic of polyandry (Figure 5b), where two conditional outcomes are

Median allele count 3 possible when the expected average number of mates of mated females matched that observed from gravid females (i.e., x̄∗ = 2). Our observa- f n = 73 offspring x̄∗ spb tions and predicted m were consistent with a mean and variance of a 2 male mate frequency distribution exhibiting polyandrogyny (Figure 5c), and consistent with a mean and variance of a male mate frequency dis- 1357911 13 15 17 tribution characteristic of polygynandry (Figure 5d). We evaluated a po- Rank of Brood Means & Medians x̄∗ tentially upward-­biased m from possible sampling error in the ASR, due to underestimating adult males and/or unmated males, which would FIGURE 4 Effect of female mating strategy on the genetic diversity of broods: monandrous mating females were revealed from decrease the total average male mating success of mated and unmated (effectively) single paternity broods (circles); polyandrous mating x̄ x̄∗ = 2.4 males, m, to less than the mated male average, m (Fig. S1). females were revealed from multiple paternity broods (dots). (a) The sampling distributions of mean observed heterozygosity for single and multiple paternity broods, ranked from lowest to highest. The 3.4 | Evaluation of the evolutionary responses of difference between the two cumulative probability distributions (not males to female spatiotemporal distributions in shown) was not significant, due to substantial overlap of variation in receptivity for S. melanops and congeners brood heterozygosities. (b) The sampling distributions of median allele richness for single and multiple paternity broods ranked from lowest to In addition to population inference for polygamy among mated highest. Multiple sired broods ranked significantly higher in median allele males, weak conspicuous sexual dimorphism, limited alternate mating richness than did single sired broods 11284 | KARAGEORGE and WILSON Jr

(a) (b) 8 x* = 2.0 35 matings f 35 ASR = BSR = 2 males/female v*f = 1.0

males 30 6 xm = x*m = 1.0, vm = v*m = 0.0 Obs. ASR = 1.2 25 Exp. mean of all/mated females: Exp. mean of mated males: xf = x*f = (1)(2) = 2 4 20 x* = (2.0) (1.2) = 2.4 VS m 15 ASR = 1, BSR = 2 (50% unmated females)

2 Freq. of males 10 Frequency of fe xf = (1)(1) = 1, x*f = (1)(2) = 2 1? 5 strong directional sex. sel. on females Ob s. 0 0 012345 12 Obs. Number of mates Number of mates

(c) (d) 10 8 17 adult males, ASR = 1.0 17 adult males, ASR = 1.0, BSR = 0.9 weak directional sex. sel. on males 8 35 matings 6 35 matings among: xm = x*m = 2.0 all males vs 15 mated males 6 vm = v*m = 0.5 weak directional sex. sel. on females 4 xm = 2.0 x*m = 2.3

4 vm = 1.4 v*m = 1.0 Freq. of male s Freq. of male s 2 2

0 0 1234 01234 Number of mates Number of mates

x̄∗ FIGURE 5 Population demographic inference on the average number of mates of the unavailable parents, mated males ( m), based on the x̄∗, v∗ mean and variance of the observed mate frequency distribution of adult females ( f f), and the observed adult sex ratio, ASR (a). The expected x̄∗ m compared to the means and variances of male mate frequency distributions characteristic of (b) polyandry, where all males mate at most once, (c) polyandrogyny, where both sexes are variable in their mating success, but more so among females, and (d) polygynandry, where both x̄∗, v∗ x̄∗ sexes are variable in their mating success, but more so among males. The observed f f, ASR, and the expected m are inconsistent with polyandry hypothesized under two different conditions (when the expected average number of mates per mated female matches that observed from the data), but are in agreement with polygamous males and polyandrogyny and polygynandry mating systems, or variations of polygamy were evident (Table 2). Among observed NT Sebastes species, males 4 | DISCUSSION search for females that are in small groups, usually consisting of multi- ple males surrounded by a single female (i.e., OSR = 1 to 7♂’s per ♀), in 4.1 | Female mate frequencies, patterns of paternity mid-­water, sometimes near conspecific schools, and males are notice- within broods, and inference for polyandrous females ably smaller than females. In contrast, among observed TT species, and a random mating pattern females with transient dichromatism search for solitary territorial or As a result of multiple male inseminations in 11 of the 17 gravid fe- lekking males, on the bottom, and males are noticeably larger. males from this natural population of Sebastes melanops, polyandrous mothers gain opportunities for direct (material) and indirect (genetic) 3.5 | The influence of the mating system on the benefits to enhance their reproductive success and offspring viability, relationship between effective population size and relative to monandrous mothers (Evans & Magurran, 2000; Newcomer reproductive failure et al., 1999). These females were sired from one to at least four males,

Our modeled rate of within-season Ne decline in response to reproduc- yielding a mate frequency distribution resembling a truncated normal tive failure of breeding adults was faster for polygamy, modeled after distribution, which could occur do to random mating. A larger sample S. melanops with two mates per adult, and for moderate polygyny, of adult females could have increased the accuracy of the estimated than those two mating systems modeled by Parker and Waite (1997). distribution, and the probability of detecting less common females in Relative to other mating systems, polygamy still conferred the highest the population with five mates, if present. Some females may have

Ne to a cohort for a fixed adult population size and a given level of repro- also failed to mate (and would represent a zero mate frequency class), ductive failure, due to weak premating sexual selection and offspring/ and/or experience reproductive failure; we found one mature female alleles of each mating male represented in two female broods (Figure 6). with an atrophied brood (discussed below). Van Doornik (2008) also KARAGEORGE and WILSON Jr | 11285

TABLE 1 Evaluation of the evolutionary responses of males to female spatiotemporal distributions in receptivity for Sebastes melanops and congeners that express schooling, nonterritorial behavior, and the supported mating system classification of S. melanops

1 Observed male–female courtship S. melanops: pair copulated twice in lower half of water column (October) ; S. emphaeus: 1 of 2 ♂’s (ca. 10 cm) and mating associations appeared to copulate ♀ (ca. 15 cm) several times, while slowly ascending from ca. 20 m to 5 m of water 1 surface, near large conspecific school (August) ; S. mystinus: ♂’s search for ♀’s in mid-water groups of 1 to 7 2 ♂’s per ♀ 1 3,4 Alternate mating strategies Sperm competitor: remating same ♀’s and possible variable sperm allocation in response to ♀ size ; sneaky copulations by ♂’s unlikely with small urogenital papilla and required ♀ cooperation for mating: slow swimming 1,2,5 speed and ventral mounting by ♂’s in water column ; alternate mating phenotypes constrained by small expected sex difference in opportunity for selection, ∆I6 (see Table S3) Sperm competition Possible, average paternity share of an ave. S. melanops brood is 62% with sperm mixing and equal paternity,a 1,5 apparent in broods sired by ≥3 ♂’s (Figure 3b); remating partners may increase ave. paternity share, reduce ♀ mating freq.; pattern of testes recrudescence in Sebastes indicates sperm still available after one or more 7 8 matings ; postmating sexual selection if some ♂’s disproportionately fertilize most/all of their mates’ ova 2 1,2 Male parental care None, ♂ energy and time devoted to searching for ♀’s, courtship persistence and displays, mating with a 1 multiple ♀’s &/or remating partner(s) Potential for sexual conflict High, premating SC over mating frequency and size-­specific fecundity,9 enhanced by polygamy10; with viviparity, possible postmating intra-­ and intergenomic conflicts b/w: parental genomes within embryos, sibling embryos, and mothers and embryos can generate genetic incompatibility and postzygotic isolation11,12 1,2 1,2,13 Sexual dimorphism Weak, except for elaborate ♂ courtship displays ; ♂’s smaller than ♀’s a possible response to ♀ search 6 2 costs and courtship persistence; urine from enlarged ♂ urinary bladders may allow ♀’s to assess ♂ reprod. status14; sex. dim. eroded by small expected ∆I6 x̄∗ = a Supported mating system Nonterritorial polygamy; exp. ave. no. of mates of mated males m 2.4, total mean ♂ mating success less with 15 unmated adult ♂’s ; population estimates and observations consistent with predicted variance in ♂ mating success for polyandrogyny or polygynandry, not effectively zero variance for polyandry (Figure 5)

Sources: 1. Following precopulatory swimming behaviors and fin-­flaring by ♂’s, copulation was described as ventral contact between partners and body quivering by ♂’s, while ♀’s slowly swim (Wayne Palsson, pers. comm., NOAA Fisheries); 2. Helvey (1982); 3. Shapiro, Marconato, and Yoshikawa (1994); 4. Marconato and Shapiro (1996); 5. Shinomiya and Ezaki (1991); 6. Shuster and Wade (2003); 7. Wyllie Echeverria (1987); 8. Shuster, Briggs, and Dennis (2013); 9. Chapman, Arnqvist, Bangham, and Rowe (2003); 10. Holland and Rice (1999); 11. Zeh and Zeh (2001); 12. Zeh and Zeh (2000); 13. Lenarz and Wyllie Echeverria (1991); 14. Stacey, Kyle, and Liley (1986); 15. Shuster (2009). Notes: Text in bold indicates a reciprocal difference between the reproductive behavior, phenotype, or ecology of Sebastes species that are demersal, often solitary as adults, and express reproductively territorial behavior. aEstimated in this study. documented broods sired by one to four males in S. alutus, although and fecundity, also influence the number of mates they choose (Jones, only 20 offspring per female were genotyped. However, the probabil- Rosenqvist, Berglund, & Avise, 2000; Trexler, Travis, & Dinep, 1997). ity of underestimating the true number of sires per brood increases Thus, multiple mates and remating with the same partner (seen with considerably when competing sires fertilize a small fraction of ova, S. melanops, Wayne Palsson, pers. comm., NOAA Fisheries), may be as we found (see also Sogard et al., 2008), requiring larger offspring important for females to obtain an adequate sperm and seminal fluid samples per brood (Jones, 2005; Neff & Pitcher, 2002). Our infer- supply, especially for prolonged sperm storage in some Sebastes spe- ence on detecting the true number of sires for each S. melanops brood cies (Takahashi, Takano, & Takemura, 1991). was achieved with high probability, based on our sampling protocols The cause(s) of the significantly skewed paternity shares we found that utilized power analysis, and simulations testing the likelihood of in all broods with two sires will remain elusive without unfeasible ex- ­observed paternity outcomes. periments that control for mating order and sperm quantity in this ex- What major factors drive the number of mates per female to vary tremely fecund, long-­lived viviparous species. Skewed paternity may in a random fashion? In terms of direct benefits, this may partly depend simply reflect variation in ejaculate quantities between sperm com- on the quantity of semen acquired per mate (sensu mate fecundity; peting males, as noted previously, due to sperm mixing and paternity Arnold & Duvall, 1994), that can covary with male differences in size/ proportional to the number of sperm inseminated per male (Wade & age, recent mating history, and their possible differential allocation Arnold, 1980; Wedell et al., 2002). These females may have mated of sperm (i.e., remating same female or not; Wedell, Gage, & Parker, with a second male due to an inadequate sperm quantity from their 2002). Importantly, the reproductive biology and few observations first mate. Sogard et al. (2008) also found skewed paternity between of rockfish mating behavior indicate mating is demanding, involving two sires in several S. atrovirens broods. Other explanations for biased ventral mounting by males in the water column while in motion, and a paternity include sperm precedence depending on mating order (Zeh small male urogenital papillae relative to body size, for internal fertil- & Zeh, 1994), cryptic female choice (Eberhard, 1996), and when the ization (Table 1); we note the sperm leakage of mating Sebastes inermis sperm from different sires vary in their genetic compatibility with a fe- seen by Shinomiya and Ezaki (1991). Female traits, including size/age male’s ova (Zeh & Zeh, 1996; discussed below). Our females that were 11286 | KARAGEORGE and WILSON Jr

TABLE 2 Evaluation of the evolutionary responses of males to female spatiotemporal distributions in receptivity for Sebastes species that are benthic/demersal, and express reproductively territorial behavior, and their hypothesized mating system classifications

Observed male–female courtship S. miniatus: ♀ courted after entering presumed territory of solitary ♂, 1 ♂ per ♀ during courtship sequences (1 1 and mating associations conspecific within 4 m of one pair), <2 m off bottom, ♂’s larger than ♀’s ; S. inermis: ♀’s search for territorial ♂’s, ♂ courtship rejection, multiple mating by ♂’s and ♀’s, remating, and sperm leakage after complex mating sequence2

Alternate mating strategies As with reprod. nonterritorial spp. (Table 1); ♀’s above bottom required for ventral mounting and internal fertilization by ♂’s 2 Sperm competition Likely in S. inermis ; large/old experienced territorial ♂’s could attain higher insemination success due to complex courtship/mating patterns, higher sperm production, and inseminate most/all of their mates’ reproductive tracts until sperm limited 1,2 Male parental care None, ♂ energy and time devoted to securing/defending mating territories , courtship displays, mating with 2 multiple ♀’s &/or remating partner(s) Potential for sexual conflict Yes, premating SC potentially greater than in reprod. nonterritorial spp. due to unique premating sexual 3 selection mechanisms: SC over mating due to ♀ preference for quality of ♂ territory (e.g., size) or position 4 effect enhancing ♀ encounter rate (e.g., highest territory on a rocky reef), and opportunities for ♀’s to copy 5 the mate choice of other ♀’s (imitative behavior) ; postmating SC with viviparity (see Table 1) 1,2 1,2,6 Sexual dimorphism Weak, except for ♂ courtship displays and territorial behavior ; larger ♂’s in territorial spp favors acquiring 2 7 mating territories; urine from enlarged ♂ urinary bladders may allow ♀’s to assess ♂ reprod. status ; lighter ♀’s 8 in S. miniatus and S. inermis during courtship aids in conspecific sex ID: ♀’s avoid territorial ♂ aggression ; sex. dim. eroded by polyandrous mating and high variation in female fecundity9 Hypothesized mating systems Territorial polygamy (strong polygynandry), convergence to polygyny possible in some species with greater sexual selection on males; territorial S. inermis exhibit major attributes of lekking species2,11

Sources: 1. Gingras et al. (1998); 2. Shinomiya and Ezaki (1991); 3. Warner et al. (1995); 4. Genner et al. (2008); 5. Dugatkin and Godin (1993); 6. see also Lenarz and Wyllie Echeverria (1991); 7. Stacey et al. (1986); 8. Noble (1938); 9. Shuster and Wade (2003); 10. Wyllie Echeverria (1987); 11. Hoglund and Alatalo (1995). Note: Text in bold indicates a reciprocal difference between the reproductive behavior, phenotype, or ecology of Sebastes species that express mid-­water/ schooling behavior as adults, and reproductively nonterritorial behavior. effectively sired by three and four males showed more even paternity progeny survive and disperse into new marine environments, they shares that would be expected with sperm mixing and paternity pro- will retain more of the genetic composition of the parent popula- portional to (compatible) sperm number per male, and when there are tion when establishing small founder populations, which experience no mating order effects biasing paternity with several sires (Zeh & Zeh, faster declines in allele richness than in heterozygosity (Luikart, 1994). Aitken, & Allendorf, 2013). Although we did not measure differences in reproductive suc- cess (RS) nor monitor the survival of progeny from monandrous and 4.2 | Effect of female mating strategy on the polyandrous females, higher allele richness in all multiple sired broods genetic diversity of broods and possible evolutionary exposes a link between the potential benefits of polyandrous mating repercussions for the viviparous Sebastes species flock and female RS. Genetic incompatibility between the gametes of mates, Other potential benefits from multiple male inseminations important such as when an incompatible allele is in a specific genotype of their to females, consistent with their random pattern of mate frequen- zygotes, can produce nonadditive genetic variation (as with overdom- cies, are more apparent from our results that show the effect of fe- inance and epistasis), with negative impacts on offspring viability and male reproductive behavior on the genetic diversity of their progeny. individual RS (Newcomer et al., 1999; Olsson & Madsen, 2001; Zeh Polyandrous mating did not increase average heterozygosity of mul- & Zeh, 1996). Bearing the hallmark signal of genetic incompatibility, tiple sired broods, relative to (effectively) monandrous females with zygote/embryo failure, Boehlert, Barss, and Lamberson (1982) found single sired broods, despite that nearly twice the number of broods/ that the percent of expected fecundity decreased with increasing progeny analyzed were from polyandrous females. This result is in embryonic developmental stage in S. entomelas, where eyed embryo agreement with life history theory, which posits that polyandrous fecundity was only 38% of the expected weight-­specific fecundity. mating is not expected to be an adaptive response to bet-­hedging for Length-­specific fecundity estimates revealed a 25% decline in larvae additive genetic variance in large populations with high genetic di- from ova numbers in S. schlegeli (Boehlert, Kusakari, & Shimizu, 1986), versity (Yasui, 1998), like those for S. melanops. Genetic diversity/Ne and a similar decline was evident between ova and zygote stages in is also maintained by large brood sizes (sensu Waples, 1987), and S. melanops (Bobko & Berkeley, 2004). By sampling sperm (and alleles) particularly by the mating system (Parker & Waite, 1997; Fig. 6, dis- from different males, polyandrous females reduce the risk of mating cussed below). Yet our discovery that allele richness was higher in with an infertile male, and gain opportunities to exploit sperm com- all multiple sired broods suggests that if a small fraction of these petition and/or female choice in their reproductive tract to assess KARAGEORGE and WILSON Jr | 11287

FIGURE 6 The influence of the major types of mating systems on the relationship between the ratio of the annual effective population size,

Ne (Wright, 1931) to the adult population size, N = 100 (sex ratio equal), and the proportion of reproductive failures due to postmating processes (male sterility, genetic incompatibility, and natural selection). Nonterritorial polygamy in Sebastes melanops, modeled with two mates per adult (filled circles), is expected to yield higher effective sizes to offspring of a cohort, compared to reproductively territorial Sebastes species with the same adult population size (moderate polygyny, open squares; extreme polygyny, open triangles), due to less opportunities for sexual selection on males. Sexual selection acting on females also reduces Ne with polyandry (filled triangles), relative to polygamy and monogamy (open circles). See text for the breeding sex ratios, the average number of mates per breeder, and the relative paternity share of broods for each mating system (modified from Parker & Waite, 1997)

oocyte–sperm genotype compatibility (Olsson & Madsen, 2001; Zeh & 4.3 | Evolutionary responses of males to female Zeh, 1997). Additionally, because Sebastes species are live-­bearing, the spatiotemporal distributions in receptivity and postzygotic reallocation of maternal resources from defective to via- inference on the mating system of Sebastes melanops ble offspring (reproductive compensation), provides a final defense to minimize the cost and/or risk of fertilization by genetically incompati- Our evaluation of male evolutionary responses to female spatiotem- ble sperm (Zeh & Zeh, 1997, 2001). Fetomaternal conflict and intrag- poral distributions in receptivity for schooling, nonterritorial Sebastes enomic conflict specific to viviparity could contribute to postzygotic species revealed evidence supporting male polygamy and a nonter- genetic incompatibility and favor the maintenance of polyandrous ritorial polygamy mating system classification for S. melanops. On a mating (Zeh & Zeh, 2001) in Sebastes species. Polygamy, inferred in fine spatiotemporal scale, we estimated that mated S. melanops males this study, can also intensify sexual conflict relative to monogamy, and mate with 2.4 females on average, though not from reconstruction increase the evolutionary potential for reproductive isolation (Holland of sires with matching multilocus genotypes between broods—an & Rice, 1999; Rice, 1998). Remarkably, despite pelagic dispersal of lar- extremely unlikely outcome given this large, open breeding popula- vae, long distance migrating adults of many species, and species over- tion. Alternatively, we integrated paternity results of the broods with lap (with multispecies aggregating schools), hybrids are mysteriously the population constraint of the ASR to estimate the average mating x̄∗ uncommon within the Sebastes species flock (for examples of excep- frequency of mated males ( m), because the mean number of mates tions, see Seeb, 1998; Muto, Kai, Noda, & Nakabo, 2013), and allopat- per mated male and female are connected through the adult sex ratio ric speciation is clearly insufficient to explain Sebastes diversification. (Arnold & Duvall, 1994; Shuster & Wade, 2003). We demonstrated However, weak premating directional sexual selection and polyan- that the observed mean and variance in mate numbers of mated fe- x̄∗ drous females, genetic incompatibility, and less frequent viable hybrids males, the ASR, and the predicted m were inconsistent with a mean among viviparous species pairs, compared to oviparous species pairs, and variance of a male mate frequency distribution exhibiting polyan- presumably due to postzygotic barriers to viable interspecific hybrid- dry, which could be possible (given female mate numbers) when the ization (and/or hybrid sterility), are also the central components of the adult sex ratio (ASR) = breeding sex ratio (BSR), is significantly male-­ Viviparity-­Driven Conflict Hypothesis for sympatric speciation (Zeh & biased, and all adults mate; or when a male-­biased BSR is significantly Zeh, 2000). greater than the ASR = 1, resulting from many unmated adult females 11288 | KARAGEORGE and WILSON Jr when females experience strong directional sexual selection. Neither if males are unable to acquire mating territories and are excluded from of these conditions were true: The ASR was actually female biased, and mating by male–male combat, rejected by female choice of territory we did not see evidence of a large fraction of unmated adult females, size/quality, or when a position effect (for example, the highest area as with viviparity it is possible to detect mating failure of adult females on a rocky reef) is related to a greater female encounter rate (Genner, due to the retention of unfertilized, atrophied broods. Moreover, fe- Young, Haesler, & Joyce, 2008). Another potential source of male fit- males do not express any elaborated secondary sexual characters ness variance is from mate copying by females (Dugatkin & Godin, that indicate strong directional sexual selection. Simply put, female 1993), especially when females aggregate around lekking and territorial mate frequencies are too high to account for males mating once, and males (Wade & Pruett-­Jones, 1990). Taken together, Imates is potentially males become even more limiting if some do not mate at all—typical greater in demersal/benthic, territorial Sebastes species, when premat- in nature. Instead, the data and predicted average number of mates ing sexual selection skews the BSR, increases variation in male repro- x̄∗ = of mated males ( m 2.4) were consistent with variable male mating ductive success (as with polygyny), which could reduce the breeding success and male mate frequency distributions that fit polygamous Ne relative to polygamy in same-­size adult populations of S. melanops. mating systems: polygynandry and polyandrogyny. Polygamy is also Moreover, reproductively territorial species can experience an elevated consistent with weak sexual dimorphism and other male evolution- risk of demographic stochasticity with greater sexual selection (Møller & ary responses to receptive females. We illustrate the importance of Legendre, 2001), and be more prone to reproductive failure, annual ge- male polygamy as an evolutionary response to polyandrous females, netic bottlenecks, and environmental stochasticity. Interestingly, many with the harmonic mean promiscuity of females. Given polyandrous demersal species that are often solitary as adults and express territorial females, sperm mixing, and equal paternity, the average S. melanops behavior, are much less common, more patchy in their distributions (and male is expected to sire about 62% of an average female’s brood, but with habitat preferences, e.g., Larson, 1980a,b), and have more harvest only 25% if his mate was previously sired by three males—far from restrictions, compared to mid-­water congeners that express schooling, complete paternity assurance relative to polyandry and monogamy. nonterritorial behavior. For some reproductively territorial species, this Consequently, a male must sire additional females and/or increase his could be partly attributable to less productive life history correlates of paternity share per female to attain greater reproductive success with population growth: greater length/age at maturity, greater maximum sperm competition, because his total expected fitness is equal to the length/age, etc. (Reynolds, Jennings, & Dulvy, 2001). For others, pro- product of his number of mates, average female fecundity, and the ductivity parameters are similar to schooling, nonterritorial species, and harmonic mean promiscuity of females (Collet, Richardson, Worley, & their mating system and behavior could reduce Ne, their per capita birth Pizzari, 2012; Shuster & Wade, 2003; Wade & Arnold, 1980). rates, and subsequent population growth. Clearly, to rebuild rockfish populations, we need more in situ observational studies of reproduc- tion and N estimates for less common territorial species—a consider- 4.4 | Conservation consequences of divergence e able challenge. Two conservation objectives, suggested by Rowe and in behavior and mating system on the relationship Hutchings (2003), we recommend here, tailored for rockfish. The first between annual effective population size and is to identify the locations of any mating territories/aggregations, with reproductive failure ROV/SCUBA, and monitor their phenology, sex-specific­ movements/ Might differences in behavior and mating systems exert differential migration patterns, and long-term­ trends in abundance. The second is impacts on the population growth rates and the recovery of exploited to collect sex-specific­ biological data on commercial/recreational catch populations of Sebastes species? The mating system assessment of of overfished and uncommon species for stock assessments ­(including S. melanops could have broader implications for the conservation of reconstructing and analyzing legacy data). Sebastes species, when the effect of nonterritorial polygamy on the re- Our mating system assessment of nonmodel S. melanops estimated lationship between annual (within-season) Ne and reproductive failure population parameters from pregnant females, their offspring, and of adults is compared to this relationship for reproductively territorial adults in the breeding population to conclude that multiple mating is congeners. With weak premating sexual selection in a resource-­free, common in both sexes. Polygamy is also consistent with male evolu- polygamous breeding population, annual Ne is relatively high before tionary responses to female receptivity for S. melanops and congeners postmating selection, and Ne is highest for a given level of cumulative with a mid-­water, schooling, and nonterritorial life history as adults, and reproductive failure of a cohort (Figure 6; Parker & Waite, 1997). In with weak expected premating directional sexual selection on males; contrast, the S. inermis mating habits observed by Shinomiya and Ezaki all support nonterritorial polygamy. Among mating systems, nonterrito-

(1991) revealed that territorial males defend courtship display/mating rial polygamy confers the highest annual Ne to cohorts, but evaluations territories (see also Gingras et al., 1998 for Sebastes miniatus). A fuller of mating system determinants of congeners with a demersal/benthic, significance of their study became evident during our evaluations of reproductively territorial life history revealed they have more possible mating system determinants in the two major life history groups: S. in- mechanisms for generating premating sexual selection and a reduced Ne ermis meet all the basic physiological and ecological prerequisites for a to cohorts, compared to S. melanops. Such a reproductive strategy may lekking species (reviewed in Hoglund & Alatalo, 1995). The opportunity be less conducive to population growth and recovery from exploitation. for directional sexual selection on males (due to high variance in male While the fundamental statistical relationships which could best mating success, Imates; Table S3) is expected to rise in territorial species quantify a mating system (i.e., Bateman Gradients) will likely remain KARAGEORGE and WILSON Jr | 11289 elusive in wild, nonmodel species in the marine realm, our multidisci- Bartley, D. M., Kent, D. B., & Drawbridge, M. A. (1995). Conservation of plinary approach that integrated mating system measures and repro- genetic diversity in a white seabass hatchery enhancement program in southern California. In H. L. Schramm, & R. Piper (Eds.), American fisher- ductive life history within the framework of sexual selection theory ies society symposium, Vol. 15 (pp. 249–258). Bethesda, MD: American has revealed an important window into the mating systems and con- Fisheries Society. servation of the Sebastes species flock. Bateman, A. J. (1948). Intra-­sexual selection in Drosophila. Heredity, 2(Pt. 3), 349–368. https://doi.org/10.1038/hdy.1948.21 Blumstein, D. T. (1998). Female preferences and effective population ACKNOWLEDGMENTS size. Animal Conservation, 1(3), 173–177. https://doi.org/10.1111/ acv.1998.1.issue-3 We are pleased to express appreciation to Elsa Torres for labora- Bobko, S. J., & Berkeley, S. A. (2004). Maturity, ovarian cycle, fecundity, and tory assistance and to S. Arnold, A. Jones, E. Shultz, S. Shuster, and age-­specific parturition of black rockfish (Sebastes melanops). Fishery Bulletin, 102(3), 418–429. K. Young for suggestions on earlier manuscript versions. We also Boehlert, G., Barss, W., & Lamberson, P. (1982). Fecundity of the widow thank Marty Gingras and Wayne Palsson for describing their obser- rockfish, Sebastes entomelas, off the coast of Oregon. Fishery Bulletin, vations of wild Sebastes reproductive behavior. We are grateful for 80(4), 881–884. the financial support provided by the Southern California Academy Boehlert, G. W., Kusakari, M., & Shimizu, M. (1986). Energetics during em- of Sciences Student Grant Program, the SCTC Marine Biology bryonic development in kurosoi, Sebastes schlegeli Hilgendorf. Journal of Experimental Marine Biology and Ecology, 101(3), 239–256. https:// Educational Foundation, the Department of Biological Science’s doi.org/10.1016/0022-0981(86)90266-2 Richard B. Loomis Foundation at California State University Long Chapman, T., Arnqvist, G., Bangham, J., & Rowe, L. (2003). Sexual conflict. Beach, and Biological Sciences Chair B. Livingston. Trends in Ecology & Evolution, 18(1), 41–47. https://doi.org/10.1016/ S0169-5347(02)00004-6 Collet, J., Richardson, D. 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