||Intrapopulation variability in a functional trait: susceptibility of Daphnia to limitation by dietary fatty acids
||Ilić, M.; Cordellier, M.; Fink, P.
||T5 Future Landscapes
||Daphnia; freshwater ecosystems; intraspecific competition; polyunsaturated fatty acids; trait‐based approach
- Functional traits are measurable characteristics of
an organism that have an impact on its fitness. Variation in functional
traits between and among species has been suggested to represent the
basis for competition and selection, thus allowing for evolution in
- In freshwater ecosystems, the availability of
essential polyunsaturated fatty acids (PUFAs), in particular ω3‐ and
ω6‐PUFAs, determines the food quality of phytoplankton for the
herbivorous zooplankton Daphnia, an unselective filter feeder.
The content of such essential PUFAs in the phytoplankton is thus a
functional phytoplankton trait affecting the trophic transfer efficiency
and dynamics at the pelagic plant–herbivore interface.
- In turn, the susceptibility of consumers to become
limited by the availability of essential PUFAs is a fitness‐determining
trait of Daphnia genotypes, and variability of this herbivore
trait may thus affect the daphnids’ intrapopulation competition. To
estimate the intrapopulation variation in susceptibility, we isolated
clonal lines of Daphnia longispina from a natural population and
compared the strength of their limitation by dietary PUFA availability
via standardised laboratory growth assays. We used a liposome
supplementation technique to enrich a PUFA‐poor green alga with
essential ω3‐ and ω6‐PUFAs and determined juvenile somatic growth rate
of different D. longispina genotypes as a fitness proxy.
- As expected, D. longispina genotypes that
coexisted in a natural population differed markedly in their specific
patterns of susceptibility to dietary PUFA availability. On average, the
D. longispina population was more strongly susceptible to
limitations in the availability of the ω6‐PUFA arachidonic acid (20:4ω6)
than to limitations in the availability of ω3‐PUFAs α‐linolenic acid
(18:3ω3) and eicosapentaenoic acid (20:5ω3).
- The ability to cope with PUFA limitation is thus a crucial trait that can probably affect intraspecific competition and Daphnia
population structure. Therefore, we suggest that such intrapopulation
variation in susceptibility to absence of dietary PUFAs might be one of
the driving forces of natural selection and local adaptation among
|Persistent UFZ Identifier
|Ilić, M., Cordellier, M., Fink, P. (2021):
Intrapopulation variability in a functional trait: susceptibility of Daphnia to limitation by dietary fatty acids
Freshw. Biol. 66 (1), 130 - 141