Rev.Biol. Trop., 42(3): 611-622, 1994 Reproductive trends, habitat typeand body characteristcs . in velvet worms (Onychophora) Julián Monge-Nájera Centro de Investigación General, UNED.Mailing address: Biología Tropical, UniversidAd de Costa Rica, San José, Costa Rica. (Rec. 4-Vll-1994. Acep. 5-IX-1994) Abstract: A quantitative analysis ofseveral onychophoran characteristics shows that in habitats with lower rain levels females reproduce at an older age, are more fecund and tend to have reproductive diapause where rain does not exceed a mean of 200cmlyear.These habitat characteristics are associated with the southem family Peripatopsidae. Sex ratio and parental investment per young are not correlated with general environmental conditions. A comparison of 72 species showed that larger species are oftenmore variable in morphóliletry, but species with the longest females do not always have the longest males. Larger Peripatus acacioi females (peripatidae: Brazil) produce more and heavier off­ sprlng. Intrapopulationmorphology was studied iti 12 peripatid species for which samples oí between 11 and 798.indi­ viduals were available. In general, within populations theíemales are more variable than males in length and weight, but similarly variable in the number of legs. The number of legs has a low variability (1. 73-2.45%), length is interme­ diate (22. 4-25. 3%) and weight is very variable (49. 41-75 . 17%). When sexes are compared within a population, females canhave 1. 4-8. 9 % more leg pairs, and be 47-63 % heavier,and26 % lóngerthan males. Key words: Body sire, sex ratio, plÍrelltal investment, legs, length, weight, evolutionary ecology. The analysis of reproductive trends in the ment in a large onychophoran sample, but the phylum Onychophora has been limited by the data have been available for years in the report fragmentarynature of the data (Read 1985).The of Lavallard and Campiglia (1975) and will be general conclusions so far have been that most re-analyzed here. studied,species make a relatively high parental The Peripatidae, one of the two families of investment in their offspring(particúlarly those the phylum, has a tropical distribution and in from the Neotropics), and that reproductive comparison withthe temperate Peripatppsidae, diapause does not seem to follow a simple geo­ has species of a larger body size,and more legs graphical pattern (Read 1985, Ruhberg 1985, which vary significantly in number (Bouvier Morera et al. 1988). 1905, Ruhberg 1985). What ecological factors may have influ­ There are few stu�es analysing populations enced such characters as age at frrst repróduc­ rather than species'ranges (reviews in Read tion, parental investment arid fecundity have 1985 and Ruhberg 1985). Nevertheless, it is received little if any attention (Read 1985, known that within a species, females tend to be Moreta el al. 1988,Havel et al. 1989). largér (e. g. 2.7 times heavier) and may be 50 % Similar�y;any possible associations between longer'than males (Campiglia and Lavallard reproduction and body characteristics have 1973, Monge-Nájera and Morera 1994). The only been considered in a qualitative way (e. g. growth late varies with the species and is high­ Ghiselin 1974). There is no published regres­ er in females and in captivity (e. g. Peripatus sion of maternal mass, fecundity and invest- acacioi 0.185-0.676, Epiperipatus edwardsii 612 REVISTADE BIOLOGIA TROPICAL 0.65, Epiperipatus imthurni 4.77, Macro­ appear pooled when tbere was no statistícal dif­ peripatus torquatus: females 5.7, males 3, gen­ ference. eral in the wild 1.62, all units are mg/day; Read The data for length and number of leg pairs 1985). (Table 3) were taken from taxonomic descrip­ Although fue original proposal of using fue tions andoften refer to preserved specimens. number of legs to distinguish species (De Blain ville, in Gervais 1838) was unjustified (Bouvier Analysis within populations: Morpho­ 1905), fue character is often usefuI to distin­ metrie data from around the world were taken guish fue sexes within a species (Bouvier 1905, from tbe literature and analysed with nonpara­ Lavallard and Campiglia 1973). Males have a metrie tests, which are fit for tbis type of data lower number of legs (Gaffron 1885, Lavallard (sources in Table 5). and Campiglia 1973, Monge-Nájera and Morera 1994) and show more cases of asym­ RESULTS metry, in which one side of the body has at least one additionalleg (fuere is no right 01' left Family comparison: When eompared wifu trend: Lavallard andCampiglia 1973). fue tropical family Peripatidae (Table 1), the A weak statistical test failed to disco ver a southem Peripatopsidae show a higher frequen­ relationship between weight and the number of ey of reproduetive diapause, longer female legs in Peripatus acacioi (Campiglia and maturation (mean 30 months against 15 of Lavallard 1973), and fue same resulted from Peripatidae) and higher feeundity (mean 23 stronger tests applied to Macroperipatus young per year against 9 of Peripatidae). The torquatus and E. trinidadensis (Read 1985). In age sample is too small for any statistieal test, contrast, heavier newborn E. imthurni have but fecundity differs significantly (Student's t more legs (Read 1985). The reason for this p<0.05). Parental investment per young is un­ variability is unknown but suggests different signifícantly higher in Peripatidae (mean 6.9 % selective pressures upon species. against 4.6% in Peripatopsidae, Student's t This paper, based on simple statistical tests, p>0.05). examines tbe relatíonship between habitat type Peripatid species have higher mean values and reproductíve and morphological character­ for minimum length and for minimum and istics of several onychophoran species, consi­ maximum number of legs in both sexes, and dering species charaeteristics (both families) Peripatid females are more variable in number and variations withinpopulations (Peripatidae). of legs than peripatopsid females (Table 4, Mann-Whitney U tests, p=0.0000-0.042). MATERIAL AND METHODS Peripatopsid males are longer (maximum length) and both sexes are more variable in Analysis at the species level: Information length (Table 4, Mann-Whítney U tests, from the literature was compiled (Tables 1-3) p=0.OOOO-0.03). There is no difference between and anaIysed witb (a) Spearman rank eorre1a­ families in maximum female lengtb and in vari­ tions, whose eoefficients are indicated by a "e" ability in tbe nurnber of legs per male (Table 4, in the text (ordinal and eontinuous variables: Man-Whitney U tests, p>O.05). "number of legs", "body lengtb", "age at first parturition", "feeundity" and "parental invest­ Character associatious with habitat: In ment"). Only significant (p<0.05) correlations most cases, reproductive charaeters were not of 0.70 or higher were included (b) tbe Mann­ correlated among tbemselves or witb environ­ Whitney U or Student's t tésts (eontínuous and mental eonditions (Table 1). The exeeptions ordinal variables eompared for the binomial were (1) a tendency of females to begin repro­ variable "reproductive frequency"), 01' (c) Chi­ ducing at a younger age in moister habitats square or Fisher Exact tests as required by sam­ (Spearman p<0.05) and (2 ) the preponderanee pIe size (cases involving tbe other variables, of reproductive diapause when mean rainfall is which are categorical). Data for categorieal below 200 cm per year (Fisher p=O.OOOl). The variables were pooled in two by two tables as diapause was also associated witb two climate fit for sample size. Males and females were types: "Warm with Dry Winter" and "Damp analysed independently in each family, but data Temperate" (Fisher p=0.034). Parental invest- MONGE-NAJERA: Reproductiveand body characteristicsin Onychophora 613 TABLE 1 Reproductive characteristics and environmental conditions for 24 onycllOphoran species * Taxaan d PI RF AF FEC QV VG PH CL TP MR RA characters Peripatidae Epiperipatus 5. 95 2 4< 26. 6< 4 5 hilkae Plicatoperipatus 12 2 10-20 2 26.6< 3 5 jamaicensis Peripatus 7. 95 15-23 1-8 6 4 3 21. 1 4 acacioli Epiperipatus 6. 5 2 2 26.6< 4 5 brasiliensis Epiperipatus 6. 7 2 2 26.6< 4 5 isthmicola Macroperipatus 5. 3 2 20. 5 7. 4 2 26.6< 3 5 torquatus Epiperipatus 5. 1 2 12. 2 16. 9 2 26.6< 3 5 imthurni Peripatus 7. 5 2 2 26.6< 3 5 juliformis Epiperipatus 7. 6 2 2 26. 6< 3 5 trinidadensis Epiperipatus 4.4 2 2 26. 6< 3 5 edwardsii Typhloperipatus 3 3 21.1 4 williamsoni Peripatopsidae Metaperipatus 2 2 2 4 10 3 5 blainvillei Metaperipatus 2 20 3 3 3 21.1 2 costesi Opisthopatus 2 3 4 2 3 21. 1 3 cinctipes Peripatopsis 24 6-10 3 4 2 3 21.1 3 moseleyi Peripatopsis 3. 7-8 5-23 3 3 2 3 21. 1 2 3 capensis Peripatopsis 3 3 2 3 21.1 2 3 balfouri Continued 614 REVISTA DE BIOLOGIA TROPICAL Peripatopsis 8-10 3 3 2 3 21. 1 2 3 sedgwicki Peripatoides 2 4 2 4 10 4 5 novae-Zealandiae Paraperipatus 2 5 2 26. 6< 5 5 novae-britanniae Ooperipatus 14 2 5 4 21. 1 2 3 sp. Peripatoides 2 36 53 2 3 4 21. 1 2 3 orientalis Euperipatoides 2 2 4 21. 1 2 3 leuckarti Euperipatoides 3. 3 2 3 4 21. 1 3 gilesi PI Parental investment as % of mother' s body weight per young. RF Reproductive frequency: 1 seasonal, 2 non-seasonal. AF Age of fernaleat first parturition, in months (lower values used for regression). FEC Fecundity (number of young borneach year per female, mean value used for regression). QV Habitat vegetation type during theQuaternary, 18000 ybp, 1 seasonal forest, 2 cold deciduous arid forest, 3 cold decidu­ ous forest, 4 cold deciduous moist forest, 5 seasonal tropical forest, 6 drought seasonal forest and grassland (after Anonymous 1988).