Molecular Phylogenetics and Evolution 41 (2006) 472–495 www.elsevier.com/locate/ympev Species diversiWcation patterns in the Polynesian jumping spider genus Havaika Prószyjski, 2001 (Araneae, Salticidae) Miquel A. Arnedo ¤, Rosemary G. Gillespie 1 Division of Insect Biology, University of California-Berkeley, ESPM 201 Wellman Hall, Berkeley, CA 94720-3112, USA Received 30 March 2006; revised 10 May 2006; accepted 13 May 2006 Available online 20 May 2006 Abstract Hotspot archipelagoes provide exceptional models for the study of the evolutionary process, due to the eVects of isolation and topograph- ical diversity in inducing the formation of unique biotic assemblages. In this paper, we examine the evolutionary patterns exhibited by the jumping spider genus Havaika Prószyjski, 2001 in the Polynesian islands of the Hawaiian and Marquesas chains. To date, systematic research on Havaika has been seriously limited by the poor taxonomic knowledge on the group, which was based on a handful of specimens that showed continuous variability and lacked clear-cut diagnostic characters. Here, we circumvent this problem by inferring a phylogeny based on DNA sequences of several fragments including both mitochondrial (protein coding cytochrome oxidase I, NAD1 dehydrogenase, ribosomal 16S, and tRNA leu) and nuclear (internal transcribed spacer 2) genes, and a statistical morphological analyses of a large sample of specimens. Results suggest that the Marquesan and Hawaiian Havaika may be the result of independent colonizations. Furthermore, data provide little support for the standard “progression rule” (evolution in the direction of older to younger islands) in Hawaiian Islands. This may be explained by a recent arrival of the group: age estimates of the diVerent lineages suggest that Havaika colonized the Hawaiian Islands after most of the extant islands were already formed. The lack of clear-cut diagnostic characters among species may also be explained by the recent origin of the group since molecular data do not provide any evidence of hybridization among lineages. Quantitative morphological data coupled with the phylogenetic information allow us to reevaluate the current limitation of Havaika taxonomy. Molecular data support the existence of at least four diVerent evolutionary lineages that are further morphologically diagnosable. However, genealogical relationships are better predicted by geographical aYnity (i.e. island) than by morphological characters used in the original descriptions of the species. A pattern of size segregation linked to largely overlapping distributions of some of the species hints at a potential involvement of competition in generating morphological diversity. This study contributes to our understanding on the origin and shaping of the biodiversity of oceanic islands and sets the stage for more detailed studies on particular aspects of these previously overlooked spiders. © 2006 Elsevier Inc. All rights reserved. Keywords: Salticidae; Hawaiian islands; Marquesas; Competition; Island evolution; Phylogeny 1. Introduction pie, 1998; Simon, 1987), and development of communities (Gillespie, 2004) and ecosystems (Vitousek et al., 1998). In The Hawaiian Islands are often considered a natural the context of evolutionary biology, studies have shown the laboratory for evolution, allowing studies of patterns of importance of isolation that the islands provide in allowing diversiWcation and species formation (Roderick and Gilles- ecological exploration and adaptive radiation (Carson and Sato, 1969; Gillespie, 2005; Vandergast et al., 2004). It has recently been shown that the proportion of species * Corresponding author. Present address: Departament de Biologia Ani- endemic to an oceanic island is related linearly to its species mal, Universitat de Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain. richness, from which it was inferred that species diversity Fax: +34 93 403 5740. may drive diversiWcation (Emerson and Kolm, 2005). This E-mail addresses: [email protected] (M.A. Arnedo), gillespi@ nature.berkeley.edu (R.G. Gillespie). relationship suggests that competition not only plays a key 1 Fax: +1 510 642 7428. role in structuring biological communities (Gillespie, 2004), 1055-7903/$ - see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.ympev.2006.05.012 M.A. Arnedo, R.G. Gillespie / Molecular Phylogenetics and Evolution 41 (2006) 472–495 473 but also may act as a selective agent triggering species (Prószyjski, 2002). Diagnostic characters are restricted to the diVerentiation. Indeed, character displacement, an outcome bulb of the male palp (Prószyjski, 2003) and the pattern, dis- of interspeciWc competition due to limiting resources, tribution, and color of setae around the chelicerae and eyes appears to be more widespread in nature than previously (Simon, 1900). Although these characters cannot be used for thought (Losos, 2000), and its key role has been implicated species identiWcation, they do serve to separate Hawaiian in the evolution of diversity in many adaptive radiations species into three phenetic groups: species with reddish and (Schluter, 2000a). white setae covering the proximal anterior part of the chelic- Several spider groups with Hawaiian endemic lineages erae and with long male palpal tibia [H. albociliata (Simon, have been used as models for the study of diVerent aspects 1900), H. canosa (Simon, 1900), H. pubens (Simon, 1900), and of the evolutionary process. Ecological shifts have played a H. valida (Simon, 1900)] and species with chelicerae covered major role in the diversiWcation of the spider genus Tetrag- with long white bristles forming lines, and with a short male natha (Blackledge and Gillespie, 2004; Gillespie, 2004), palpal tibia. The latter group is further divided into species while speciation in the endemic spider Orsonwelles has been with a long male bulb embolus [H. cruciata (Simon, 1900), H. mostly driven by inter-island colonization (Hormiga et al., jamiesoni Prószyjski, 2001, H. navata (Simon, 1900)] and 2003). In all spider groups examined to date, species on species with a short embolous [(H. senicula (Simon, 1900) younger islands appear to have been derived from ances- and H. verecunda (Simon, 1900)]. The absence of clear-cut tors on older islands, which is in accordance with prevailing limits separating species in Hawaiian Havaika could be “progression rule” found in the large majority of lineages explained by a recent diversiWcation of the group with insuY- within the Hawaiian Islands (Funk and Wagner, 1995). cient time for Wxation of diagnostic characters. Alternatively, The current study uses a unique system of jumping spi- species limits may have been secondarily obscured as a result ders: the genus Havaika Prószyjski, 2001 (Araneae: Saltici- of recurrent hybridization events. Indeed, occurrence of nat- dae) in the Hawaiian Islands. Havaika is one of the most ural hybridization has been documented in several Hawaiian species-rich salticid genera in the PaciWc region, only sur- arthropod taxa, including Drosophila (Carson, 1989), Lau- passed by Sobasina Simon, 1898 from the western PaciWc pala crickets (Shaw, 1996), and Megalagrion damselXies (Jor- (Berry et al., 1998). It currently comprises three species in dan et al., 2003). the Marquesas (Berland, 1933, 1934) and nine species in the An additional biogeographic puzzle presented by the Hawaiian Islands (Prószyjski, 2002; Simon, 1900) although genus Havaika is the inclusion of the Marquesas islands, in given the status of knowledge of other spiders groups (e.g. addition to Hawaii, in its distribution (Berland, 1933, 1934). Tetragnatha) prior to recent research, the possibility of Biological similarities across PaciWc islands, in particular many more undescribed species is evident (Gillespie, 1999). among snails (Pilsbry, 1900), certain insects (Meyrick, Recent research using molecular characters for the entire 1935a,b), spiders (Berland, 1942), and plants (Brown, 1921; family Salticidae, which included 81 genera broadly scat- Campbell, 1933; Guillaumin, 1928) led scientists in the ear- tered throughout the more than 500 known genera accord- lier part of the 20th century to propose the existence of an ing to previous notions of the phylogenetic diversity of the extensive land mass (submerged around the early Tertiary) family, has identiWed the continental genera Pellenes in the area currently occupied by the PaciWc depression Simon, 1876 and Habronattus F. O. P.-Cambridge, 1901 as (Gregory, 1930). However, considerable evidence now the closest relatives of Havaika (Maddison and Hedin, exists to support the hypothesis that the islands within the 2003b). These results are further supported by somatic and PaciWc depression are of volcanic origin and acquired their genitalic morphological similarities (Prószyjski, 2002). The faunas by overseas dispersal (Gregory, 1928): The Hawai- genus Habronattus (Masta and Maddison, 2002) is well ian archipelago originated from a volcanic hotspot (Wil- known for elaborate male secondary sexual characteristics, son, 1963), and the islands of the Marquesas were formed in with sexual selection having been demonstrated to play a a similar fashion, though from diVerent hotspots (Nunn, prominent role in species diversiWcation (Masta and Madd- 1994). Nevertheless, molecular evidence has recently indi- ison, 2002). However, Havaika males, very much like Pel- cated biogeographic connections between the remote lenes males, have only mild ornamentation that shows PaciWc islands. The