SEASONAL SUCCESSION AND CONGENERIC ASSOCIATIONS OF <i>DIAPTOMUS</i> SPP. (COPEPODA) IN SOME SASKATCHEWAN PONDS1

Hammer, U. T.; Sawchyn, W. W.

doi:10.4319/lo.1968.13.3.0476

Cited by 26 publications

(9 citation statements)

References 8 publications

(22 reference statements)

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“…Pelagic systems have not been given a great deal of attention in the study of hybridization and hybrid zones, in part, due to the assumption in aquatic systems that sympatric species maintain reproductive isolation through ecological or morphological segregation (Rigler and Langford 1967;Sandercock 1967;Hammer and Sawchyn 1968). However, the existence of hybrid complexes in cladocerans as well as observations of intermediate phenotypes in freshwater copepods provide strong evidence that zooplankton species are not reproductively isolated in the ®eld (Wolf and Mort 1986;Weider and Wolf 1991;Weider 1993;Taylor and Hebert 1993a;Schwenk and Spaak 1995).…”

Section: Discussionmentioning

confidence: 94%

“…Second, the assumption underlying much research on plankton has been that sympatric congeners are reproductively isolated (Hutchinson 1951;Rigler and Langford 1967;Sandercock 1967;Hammer and Sawchyn 1968;Katona 1973;Griths and Frost 1976;Jacoby and Youngbluth 1983;Maly 1984a, b;Grad and Maly 1988;Blades-Eckelbarger 1991;Chow-Fraser and Maly 1992). Hence, few studies have examined the potential for genetic exchange among sympatric populations.…”

Section: Introductionmentioning

confidence: 98%

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The potential for hybridization in freshwater copepods

1997

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The importance of hybridization and hybrid zones in pelagic systems is largely unknown, in part because planktonic species are generally assumed to be reproductively isolated. However, lakes in their entirety represent potential hybrid zones throughout which sympatric species may mate and hybridize. Recent field evidence for the existence of intermediate phenotypes together with behavioral observations of heterospecific matings suggest that hybridization may be much more common than previously thought in these systems. This study examines the potential for hybridization of two related copepod species, Diaptomus minutus and D. pygmaeus, that co-occur in lakes throughout the northeastern United States. Field and experimental laboratory data were collected to: (1) compare the spatial and temporal occurrence of these two congeners in a single lake; (2) quantify the extent to which mating errors occur insitu; (3) examine the species specific mating cues that potentially affect the probability of hybridization; and (4) determine the potential for gametic compatibility and hybrid viability of these two species. D. minutus and D. pygmaeus are spatially and temporally sympatric, and the timing of their reproductive activity can be coincident insitu. One-directional mating errors occur frequently in both the laboratory and the field (e.g., upto 70% of D.minutus females in situ may carry spermatophores from D.pygmaeus males). Very low but successful production of hybrids also occurs, demonstrating that their gametes are indeed compatible and their hybrids are sometimes viable. These results underscore the potential for hybridization to play a greater role in speciation and contribute more to phenotypic diversity in aquatic crustacean communities than previously shown.

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Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 98%

The potential for hybridization in freshwater copepods

1997

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“…First, short-lived pools may lack some species because they dry up before species with a long period of development can complete their life cycles, while pools of longer duration provide habitat for both rapidly and slowly developing species (Hamer & Appleton, 1991 ;Hammer & Sawchyn, 1968 ;Retallack & Clifford, 1980;Simovich & Fugate, 1992 ;Thiery, 1991 ;Wiggins et al ., 1980) . Studies of developmental rates under natural temperature and food regimes for the numerous species that are found only in large, deep pools would help to test the hypothesis that these species are unable to inhabit short-lived pools due to developmental time constraints .…”

Section: Discussionmentioning

confidence: 99%

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

1996

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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 .

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“…Investigators studying calanoid copepods have compiled data in numerous instances consistent with such an hypothesis (Davis, 1961;Cole, 1961;Sandercock, 1967;Hammer & Sawchyn, 1968;Bayly & Williams, 1973;Maly, 1984a), although some data have not been consistent with this hypothesis (Rigler & Langford, 1967;Hofmann, 1979). Furthermore, dietary differences may not be a function of size: studies on particle size ingestion (Richman et al, 1980;J.D.…”

Section: Introductionmentioning

confidence: 93%