Species richness, endemism and ecology of crustacean assemblages in northern California vernal pools

Abstract

Ephemeral pools occur worldwide, provide habitat for organisms with a variety of life history strategies, and may have served as evolutionary refugia for some taxa since Mesozoic times . Yet, our understanding of the ecology and evolutionary history of ephemeral pool communities is hampered by a paucity of such basic data as the species composition of pool assemblages . We surveyed 58 vernal (ephemeral spring-time) pools from 14 sites in northern California for crustaceans, and found diverse assemblages composed largely of endemic and rare species . Sixty-seven species of crustaceans were found, and as many as 30 of these may be new, undescribed species . Differences in species composition among pools correspond with physical and chemical aspects of the habitat (depth, solutes concentration, elevation, biogeographic region), and with existing geologic/floristic-based habitat descriptions . Species richness is positively correlated with both depth and surface area . This relationship can be explained in terms of hydroperiod (accommodation of species with slower developmental rates in long-lived pools, greater time for temporal resource partitioning) and size (spatial habitat heterogeneity) . High species richness and numerous co-occurrences of congeneric species in temporary pools may be due to super-abundant resources, low levels of predation, and annual truncation of the community which prevents ecological interactions from going to completion . The results of this survey underscore the need for conservation of the vernal pool habitat and endemic vernal pool species in California . The best preservation strategy will include many pools at each site, multiple sites of each habitat type, and all identified habitat types .

Limnological aspects of an Apennine shallow lake

“…Arrows indicate the observed fish kill events. semblage the number of species was low but comparable with those of other mountain lakes (King et al 1996, Angeli et al 2002. The presence in the samples of fast swimmers such as copepods indicate this method not to be selective for some particular species (i.e.…”

“…Small freshwater systems add significant biodiversity value to a region (Collinson et al 1995, King et al 1996, Di Sabatino et al 2003. This is particularly true in the central Apennines over 1000 a.s.l.…”

Species richness on islands in time: variation in ephemeral pond crustacean communities in relation to habitat duration and size

“…Although insular biogeographic theory (McArthur & Wilson, 1967) may seem like a useful paradigm for prediction of species richness in ephemeral ponds, defining habitat size is problematic in part because pond size changes during the inundation cycle. Measures like maximum pond area can be good predictors of community richness (Brooks & Hayashi, 2002;Helm, 1998;King et al, 1996;March & Bass, 1995) but increasing habitat permanence, measured as ponding duration or hydroperiod, has also been shown to successfully predict higher species richness (Bohonak & Jenkins, 2003;Ebert & Balko, 1987;Eitam et al, 2004;Jeffries, 2001;Schneider & Frost, 1996;Wissinger et al, 1999). These studies report on different taxonomic groups from ponds with hydroperiods ranging from days to months, and in diverse ecological settings, so it is not clear if the different results are due to pond type differences or that island biogeographic theory alone is incapable of predicting species richness in temporary ponds.…”

“…However, there is no general consensus as to the extent or importance of dispersal for these organisms, which may even vary across species and habitat types (Bohonak & Jenkins, 2003). Differences in species composition among even closely spaced pools and among filling events within a pool may be attributable to random chance, or differences in life history or physiology (García et al, 1997;Graham, 2002;Hall et al, 2004;King et al, 1996;Mahoney et al, 1990;Schneider & Frost, 1996). Thus, the presence or absence of a particular temporary pond crustacean over time is likely to be due to factors other than spatial colonization and extinction.…”

Trade-Offs and Coexistence: A Lottery Model Applied to Fig Wasp Communities

“…Well-studied examples of such organisms include insects whose larvae consume organic matter in dung or carrion (Beaver 1977;Hanski 1990), in decaying leaves (Heed 1968), or in the living tissues of fungi (Jaenike and James 1991;Wertheim et al 2000), fruit (Atkinson 1985;Duyck et al 2004), or flowers (Weiblen 2002;Pellmyr 2003). Additional examples in-clude insects (Boix et al 2001;Colburn et al 2008), crustaceans (Hanski and Ranta 1983;King et al 1996;Ripley and Simovich 2008), and plants (Collinge and Ray 2009) that rely on ephemerally available vernal pools and parasites that rely on ephemerally available hosts (Hanski 1987;Grenfell and Keeling 2008). The ephemeral patches that these organisms use often support a large number of species (Atkinson and Shorrocks 1981;Hanski 1987;Hartley and Shorrocks 2002), and many theoretical and empirical studies have focused on understanding the mechanisms by which competitors using these resources are able to coexist (Shorrocks et al 1979;Atkinson and Shorrocks 1981;Chesson 2000a;Woodcock et al 2002).…”