Femtosekunden-Dynamik in Materialien mit Schichtstruktur

Institutions
  • Department of Physics
Publications
  Budweg, Arne (2019): Ultraschnelle Ladungsträgerdynamik in elektronischen Systemen mit eingeschränkter Geometrie

Ultraschnelle Ladungsträgerdynamik in elektronischen Systemen mit eingeschränkter Geometrie

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dc.title:


dc.contributor.author: Budweg, Arne

Origin (projects)

    Torres-Dowdall, Julián; Golcher-Benavides, Jimena; Machado-Schiaffino, Gonzalo; Meyer, Axel (2017): The role of rare morph advantage and conspicuousness in the stable gold-dark colour polymorphism of a crater lake Midas cichlid fish Journal of Animal Ecology. 2017, 86(5), pp. 1044-1053. ISSN 0021-8790. eISSN 1365-2656. Available under: doi: 10.1111/1365-2656.12693

The role of rare morph advantage and conspicuousness in the stable gold-dark colour polymorphism of a crater lake Midas cichlid fish

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1. Genetically based stable colour polymorphisms provide a unique opportunity to study the evolutionary processes that preserve genetic variability in the wild. Different mechanisms are proposed to promote the stability of polymorphisms, but only few empirical examples have been documented, resulting in an incomplete understanding of these mechanisms.

2. A remarkable genetically determined stable colour polymorphism is found in the Nicaraguan Midas cichlid species complex (Amphilophus cf. citrinellus). All Midas cichlids start their life with a dark-grey coloration (dark morph), but individuals carrying the dominant “gold” allele (c. 10%) lose their melanophores later in life, revealing the underlying orange coloration (gold morph). How this polymorphism is maintained remains unclear. Two main hypotheses have been proposed, both suggesting differential predation upon colour morphs as the proximate mechanism. One predicts that the conspicuous gold morph is more likely to be preyed upon, but this disadvantage is balanced by their competitive dominance over the dark morph. The second hypothesis suggests a rare morph advantage where the rarer gold morph experiences less predation. Empirical evidence for either of these mechanisms is still circumstantial and inconclusive.

3. We conducted two field experiments in a Nicaraguan crater lake using wax models simulating both morphs to determine predation pressure upon Midas cichlid colour morphs. First, we tested the interaction of coloration and depth on attack rate. Second, we tested the interaction of fish size and coloration. We contrasted the pattern of attacks from these experiments to the predicted predation patterns from the hypotheses proposed to explain the colour polymorphism's stability.

4. Large models imitating colour morphs were attacked at similar rates irrespectively of their position in the water column. Yet, attacks upon small models resembling juveniles were directed mainly towards dark models. This resulted in a significant size-by-colour interaction.

5. We suggest that gold Midas cichlids experience a rare morph advantage as juveniles when individuals of this morph are extremely uncommon. But this effect is reduced or disappears among adults, where gold individuals are relatively more common. Thus, the interaction of rare morph advantage and conspicuousness, rather than either of those factors alone, is a likely mechanism resulting in the stability of the colour polymorphism in Midas cichlids.

Origin (projects)

  Grupp, Alexander (2017): Ultraschnelle Prozesse in zweidimensionalen Materialien und an Grenzflächen

Ultraschnelle Prozesse in zweidimensionalen Materialien und an Grenzflächen

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dc.title:


dc.contributor.author: Grupp, Alexander

Origin (projects)

    Recknagel, Hans; Elmer, Kathryn R.; Meyer, Axel (2014): Crater lake habitat predicts morphological diversity in adaptive radiations of cichlid fishes Evolution. 2014, 68(7), pp. 2145-2155. ISSN 0014-3820. eISSN 1558-5646. Available under: doi: 10.1111/evo.12412

Crater lake habitat predicts morphological diversity in adaptive radiations of cichlid fishes

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Adaptive radiations provide an excellent opportunity for studying the correlates and causes for the origin of biodiversity. In these radiations, species diversity may be influenced by either the ecological and physical environment, intrinsic lineage effects, or both. Disentangling the relative contributions of these factors in generating biodiversity remains a major challenge in understanding why a lineage does or does not radiate. Here, we examined morphological variation in body shape for replicate flocks of Nicaraguan Midas cichlid fishes and tested its association with biological and physical characteristics of their crater lakes. We found that variability of body elongation, an adaptive trait in freshwater fishes, is mainly predicted by average lake depth (N = 6, P < 0.001, R2 = 0.96). Other factors considered, including lake age, surface area, littoral zone area, number of co-occurring fish species, and genetic diversity of the Midas flock, did not significantly predict morphological variability. We also showed that lakes with a larger littoral zone have on average higher bodied Midas cichlids, indicating that Midas cichlid flocks are locally adapted to their crater lake habitats. In conclusion, we found that a lake's habitat predicts the magnitude and the diversity of body elongation in repeated cichlid adaptive radiations.

Origin (projects)

Funding sources
Name Finanzierungstyp Kategorie Project no.
Schwerpunktprogramm third-party funds research funding program 412/15
Further information
Period: 01.03.2015 – 29.02.2020