Habitat use and ecological specialization within lake Daphnia populations

Tessier, Alan J.; Leibold, Mathew A.

doi:10.1007/s004420050117

Cited by 41 publications

(42 citation statements)

References 49 publications

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“…Oxygen concentrations below 1 mg L Ϫ1 appeared to set the lower limit of the population's spatial distribution later in the year (Fig. 6), a finding that is consistent with other studies of D. pulicaria (Geedy et al 1996;Tessier and Leibold 1997).…”

Section: Discussionsupporting

confidence: 79%

Seasonal and diel patchiness of a Daphnia population: An acoustic analysis

Hembre

Megard

2003

Limnology & Oceanography

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Detailed information about the location and extent of zooplankton patches is fundamental to understand how abiotic and biotic forces interact to structure the spatial distribution of zooplankton. We mapped zooplankton patchiness in a Minnesota lake during spring, summer, and autumn with high-frequency (192-kHz) single-beam sonar. Conventional plankton samples of aggregations detected acoustically revealed that Daphnia pulicaria (mean body length 1.6 mm, mean target strength Ϫ120 dB) scattered most (ϳ63%) of the sound. Other taxa were smaller (Ͻ½ the length of D. pulicaria) and were usually less abundant and therefore scattered much less sound than D. pulicaria. Our acoustic estimates of Daphnia concentrations illustrate extreme patchiness, with concentrations varying by as much as four orders of magnitude over vertical distances of less than 1 m. Seasonal patterns of patchiness were related to predation by rainbow trout and to abiotic factors associated with stratification. Daphnia concentrations were highest from June to October in a deep-water ''refuge zone'' where oxygen concentrations were between 3 and 5 mg L Ϫ1 . These oxygen levels are suitable for Daphnia but are lower than those required by rainbow trout. Heterogeneity in Daphnia concentration along the lake's long axis was highest in May and June, when the population resided primarily in the oxic hypolimnion during the daytime. From July to October, as oxygen concentrations declined in the hypolimnion, the population became more metalimnetic and more uniformly distributed in the horizontal dimension. A diel study of the population in October indicated that the patchiness of population also changed dramatically between day and night. During the day the population aggregated densely in a thin layer (ϳ2 m thick) in the thermocline. After sunset the population dispersed into the epilimnion, where concentrations were ϳ100,000 m Ϫ3 less than they were during the day in the thermocline.Patchy spatial distributions and the low resolution of conventional sampling methods have impeded analyses of zooplankton populations. Zooplankton concentrations have been shown to vary by a factor of 1,000 within distances of meters horizontally or vertically, and the sampling resolution of conventional plankton nets and hoses is usually too coarse to identify the spatial limits of aggregations precisely (Coyle 2000). Variation in population density estimates due to sampling often cannot be distinguished from real changes of population density, and the effects of biological processes are difficult to distinguish from those of advective transport (Megard et al. 1997). Acoustic and optical plankton samplers developed during recent decades are major advances. They have very high sampling rates and spatial resolution, comparable to modern instruments (e.g., CTD profilers) used to measure environmental variables. Large numbers of plank-

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Section: Discussionsupporting

confidence: 79%

Seasonal and diel patchiness of a Daphnia population: An acoustic analysis

Hembre

Megard

2003

Limnology & Oceanography

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“…The deep, cold, low-food hypolimnion is usually considered to be a hostile environment for Daphnia, and their occurrence there is interpreted as a trade-off between high risk of predation in the otherwise favourable epilimnion and survival under suboptimal temperature and food conditions (e.g., Zaret & Suffern, 1976;Stich & Lampert, 1981;Lampert, 1989;Guisande et al, 1991). On the other hand, living in a cold hypolimnion can be regarded as the colonisation of a broader spectrum of habitats available within a lake or reservoir, and thus as a mechanism facilitating the cooccurrence and increased diversity of Daphnia clones and species (Tessier and Leibold, 1997). There are three indications that the presence of D. galeata in the deep hypolimnion of Ř ímov Reservoir fits the ecological specialisation for broader habitat use rather than the trade-off strategy.…”

Section: Discussionmentioning

confidence: 99%

Daphnia galeata in the deep hypolimnion: spatial differentiation of a “typical epilimnetic” species

Seďa¹,

Kolářová

Petrusek

et al. 2007

Hydrobiologia

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Daphnia galeata is traditionally regarded to be a non-migratory species, which lives in warm epilimnetic waters. Depth segregation or vertical migration is usually attributed to other Daphnia species such as D. hyalina or D. longispina. In a two-year study, we found that in a deep, dammedvalley reservoir (Ř ímov Reservoir, Czechia) the majority of the population of D. galeata lives in the warm epilimnetic waters during the summer months, but some specimens of this species could be always found in the deep strata as well. This hypolimnetic subpopulation stays in the cold hypolimnetic water and does not migrate. The abundance of hypolimnetic D. galeata does not exceed one specimen per litre and usually shows seasonal variation (minimal densities in early spring, maximal in late summer). Using allozyme electrophoresis, we found that the subpopulation from the deep hypolimnion was clearly genetically differentiated from the population in the epilimnion. We found significant differences in both allele and multilocus genotype frequencies; the F ST values at most sampling dates exceeded 0.05. However, the spatial segregation between the epilimnetic and hypolimnetic subpopulations is not permanent. The reservoir is dimictic and hence, at least twice per year, all vertically segregated parts of the population are mixed together. Our results suggest that the deep hypolimnetic subpopulation is repeatedly re-established in spring by deepwater ''colonists'', at least some of which seem to be ecologically specialised for the hypolimnetic conditions, and dominate the hypolimnion by the end of the season. The genetic differentiation is likely the result of both the different depth preferences of various D. galeata clones and different selective pressures in the epilimnion and hypolimnion.

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“…Our goal is to illuminate possible mechanisms that promote their coexistence within the littoral zone of small North American lakes. We assess whether, and to what extent, species differ in habitat use and predation risk, two niche axes that commonly mediate competitive interactions in freshwater communities (Werner and McPeek 1994;Skelly 1995;Tessier and Leibold 1997). Although experimental studies are ultimately required to determine causal processes promoting coexistence, our observational study suggests that strong niche differentiation is possible among species with very close phenotypic similarity.…”

Section: Introductionmentioning

confidence: 97%

Niche diversity in crustacean cryptic species: complementarity in spatial distribution and predation risk

Wellborn

Cothran

2007

Oecologia

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Recent genetic studies indicate that species with very close phenotypic similarity ("cryptic species") are a common feature of nature, and that such cryptic species often coexist in communities. Because traditional views of species coexistence demand that species differ in phenotype to coexist stably, the existence of sympatric cryptic species appears to challenge traditional perspectives of coexistence. We evaluated niche diversity in three recently discovered species of Hyalella amphipods that occur sympatrically in lakes and share close phenotypic similarity. We found that, in some cases, these species exhibited strong complementary spatial distributions within the littoral zone of lakes, both across a distance-from-shore gradient, and a vertical depth gradient. Additionally, we compared fish stomach contents with habitat samples and found that species differed in their vulnerability to predation from sunfish (Lepomis spp.). Complementarity among species across axes of spatial distribution and predation risk, two important niche components, suggests that species with close phenotypic similarity may differ appreciably along ecologically relevant axes. Our results, considered in the light of previous studies, suggest a community structured by predator-mediated coexistence or sequential dominance across environmental gradients in the littoral zone.

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Habitat use and ecological specialization within lake Daphnia populations

Cited by 41 publications

References 49 publications

Seasonal and diel patchiness of a Daphnia population: An acoustic analysis

Seasonal and diel patchiness of a Daphnia population: An acoustic analysis

Daphnia galeata in the deep hypolimnion: spatial differentiation of a “typical epilimnetic” species

Niche diversity in crustacean cryptic species: complementarity in spatial distribution and predation risk

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