Contrasting Quaternary Histories in an Ecologically Divergent Sister Pair of Low-Dispersing Intertidal Fish (Xiphister) Revealed by Multilocus Dna Analysis

Abstract

Abstract. Recurrent glacial advances have shaped community histories across the planet. While biogeographic responses to glaciations likely varied with latitude, the consequences for temperate marine communities histories are less clear. By coalescent analyses of multiloci DNA sequence data (mitochondrial DNA control region, ␣-enolase intron, and ␣-tropomyosin intron) collected from a low-dispersing sister pair of rocky intertidal fishes commonly found from southeastern Alaska to California (Xiphister atropurpureus and X. mucosus), we uncover two very different responses to historical glaciations. A variety of methods that include a simulation analysis, coestimates of migration and divergence times, and estimates of minimum ages of populations sampled up and down the North American Pacific coast all strongly revealed a history of range persistence in X. atropurpureus and extreme range contraction and expansion from a southern refugium in X. mucosus. Furthermore, these conclusions are not sensitive to the independent estimates of the DNA substitution rates we obtain. While gene flow and dispersal are low in both species, the widely different histories are rather likely to have arisen from ecological differences such as diet breadth, generation time, and habitat specificity. The periodic glacial epochs of the Quaternary were prolonged and occupied nearly 80% of the last 2 million years (Lambeck et al. 2002). The composition of Northern Hemisphere temperate communities during warmer interglacial periods such as the current Holocene era is widely thought to be the result of range expansion and colonization from southern glacial refugia, leading to directional selection favoring generalists with higher dispersal ability and lower overall taxonomic diversity than tropical regions (Valentine and Jablonski 1993; Hewitt 1999;Dynesius and Jansson 2000). While these glaciations have often resulted in genetic signatures of low population divergence and gradients in genetic diversity in temperate North American and European taxa (Avise 2000; Hewitt 2000;Lessa et al. 2003), some genetic studies are increasingly suggesting that many temperate communities consist of taxa that retained the geographical extent of their ranges in cryptic multiple refugia (Stewart and Lister 2001;Jacobs et al. 2004).The community composition of temperate intertidal areas such as the northeastern Pacific is likely to be the result of both historical processes such as these cyclical glaciations as well as contemporary oceanographic processes and changes (Horn and Allen 1978;Roy et al. 1995;Lindberg and Lipps 1996; Roy et al. 2001;Hohenlohe 2004). The craggy and complex coastline of the northeastern Pacific intertidal contains a highly diversified biota, yet it has experienced coastal sea ice, lower sea surface temperatures (SST), shifts in major current patterns (Sabin and Pisias 1996;Lyle et al. 2000;Herbert et al. 2001;Pisias et al. 2001), and sea levels falling as much as 150 m (Pielou 1991;Williams et al. 1998;Rahmstorf 2002 this community during...

Estimating a Geographically Explicit Model of Population Divergence

“…Application of these approaches to multilocus data in the montane grasshopper M. oregonensis illustrates how such a population-divergence model might be inferred. Although several caveats warrant caution in this endeavor, this study signifies an important shift in how geographically structured species can be studied-in this case, estimation of model of population divergence (e.g., Milot et al 2000;Hickerson and Cunningham 2005;Buckley et al 2006;DeChaine and Martin 2006) that incorporates the geographic structure associated with displacements into glacial refugia and recolonization of the sky islands of the northern Rocky Mountains. Historical signal is separated from stochastic noise to estimate population relationships (Fig.…”

“…Similarly, models that accommodate multiple populations (Beerli 2002) and their historical associations (Rannala and Yang 2003) are critical to studying divergence in geographically structured species. The relationships among populations, or the population tree (Maddison 1997), may be of central interest itself, as with testing hypotheses about the geography of divergence where different population trees (topologies) represent alternative historical scenarios of differentiation within species (e.g., Milot et al 2000;Knowles and Maddison 2002;Carstens et al 2005a;Hickerson and Cunningham 2005;Buckley et al 2006;DeChaine and Martin 2006), or the focus may be on estimating genetic parameters, where the estimates depend upon the specifics of the population tree (Rannala and Yang 2003). In both cases, the topology of the population-divergence model (i.e., population relationships and historical associations) is a parameter with far-reaching consequence on population-genetic analyses of the divergence process.…”

Evolution of Poecilogony From Planktotrophy: Cryptic Speciation, Phylogeography, and Larval Development in the Gastropod Genus Alderia

“…However, the higher haplotype diversity and mean number of pairwise differences in A. modesta are also consistent with a larger pre-expansion population. The ability of long-lived larvae to disperse across the Pacific may have allowed the cold-adapted A. modesta to migrate between viable patches during glacial maxima, escaping population crashes associated with regional glaciation (Warner et al 1982;Marko 2004;Hickerson and Cunningham 2005).…”

Cryptic Vicariance in Gulf of California Fishes Parallels Vicariant Patterns Found in Baja California Mammals and Reptiles

“…For example, climatic variability during the Pleistocene may have increased speciation rates (Bermingham et al 1992;Arbogast and Slowinski 1998;Randall 1998;Barber et al 2000;Knowles 2000Knowles , 2001Johnson and Cicero 2004, but see Cracraft and Prum 1988, Klicka and Zink 1997, Williams and Reid 2004. Similarly, these processes also may have affected patterns of genetic variation within species (Avise et al 1998;Wares and Cunningham 2001;Hickerson and Cunningham 2005, but see Klicka and Zink 1999). Modern intraspecific divisions could have resulted from two nonmutually exclusive processes.…”