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Co-existence of calopterygid damselfly species: neutrality or negative frequency dependence?

Rivas, Anais (2015) BIOP01 20142
Degree Projects in Biology
Abstract
Closely related species often share the same local environment and use similar resources. Local diversity could then be maintained through some frequency-dependent species maintenance mechanism, fulfilling the invasibility criterion. Alternatively, and according to the neutral theory of biodiversity, different species should randomly go extinct over time. Here, I studied two closely related and congeneric damselfly species (Calopteryx splendens and Calopteryx virgo) to investigate if, how and why species with similar ecology could coexist. Through an experimental investigation in large outdoor cages, I investigated if there was any evidence for either species neutrality or coexistence via negative frequency dependent survival advantages of... (More)
Closely related species often share the same local environment and use similar resources. Local diversity could then be maintained through some frequency-dependent species maintenance mechanism, fulfilling the invasibility criterion. Alternatively, and according to the neutral theory of biodiversity, different species should randomly go extinct over time. Here, I studied two closely related and congeneric damselfly species (Calopteryx splendens and Calopteryx virgo) to investigate if, how and why species with similar ecology could coexist. Through an experimental investigation in large outdoor cages, I investigated if there was any evidence for either species neutrality or coexistence via negative frequency dependent survival advantages of rare species. I quantified the longevity of both species under several different density and frequency treatments, where the number and species composition in the cages was manipulated in a fully factorial experimental design. My results suggest that longevity of these two species was similar over a large range of densities and frequency treatments, except when total male density was low and the frequency of C. splendens males was high. In this situation, C. virgo males showed evidence of a negative frequency-dependent survival advantage. I also present data on species-specific territoriality and discuss how territorial plasticity might contribute to coexistence between the two species. I found that C. virgo was significantly more likely to be territorial in two out of six density -and frequency treatments than was C. splendens. Overall, my results are consistent with species neutrality across most density and frequency-environments, although there is also evidence for negative frequency dependent fitness advantage of C. virgo at low density and when C. splendens was common. Therefore, different outcomes would be expected when these two ecologically similar and congeneric damselflies come in to contact with each other in nature, depending on environmental context. (Less)
Popular Abstract
How two similar damselfly species can co-exist?

Nowadays, one can not a priori assume that each and every species found together in a local community need to coexist in the long run. Instead, local community composition might follow a neutral community dynamics, whereby species are expected to randomly go to extinct. However, ecologically equivalent species cannot coexist infinitely, so there needs to exist some coexistence mechanism (-s) if two or more species are going to continue to coexist locally.
The aim of my project was experimentally investigate and search for potential co-existence mechanisms between two ecologically similar damselfly species within the same genus (Calopteryx splendens and Calopteryx virgo). In particular,... (More)
How two similar damselfly species can co-exist?

Nowadays, one can not a priori assume that each and every species found together in a local community need to coexist in the long run. Instead, local community composition might follow a neutral community dynamics, whereby species are expected to randomly go to extinct. However, ecologically equivalent species cannot coexist infinitely, so there needs to exist some coexistence mechanism (-s) if two or more species are going to continue to coexist locally.
The aim of my project was experimentally investigate and search for potential co-existence mechanisms between two ecologically similar damselfly species within the same genus (Calopteryx splendens and Calopteryx virgo). In particular, I investigated the importance of neutrality or coexistence through negative frequency dependence mechanisms (i.e. that a species does better when it is rare than when it is common). In addition, I also investigated how territoriality behaviour of these two species changed in relation to local community composition in the form of density and frequency of interacting species.
In order to examine the coexistence mechanism (-s) I estimated longevity of individually marked damselflies of these two species in different density and frequency-environments in large outdoor cages, where the total number of individuals and damselfly species composition was experimentally manipulated. My study demonstrate experimental data suggesting that a mixture of neutrality and negative frequency dependent shape the coexistence of these two ecologically similar damselflies. These results also suggest that these two damselfly species use different degree of territoriality (i.e. more probability to holding a territory or less probability to holding a territory) depending on the other species territorial behavior. This study is one of few experimental studies of this kind, where species composition (frequency) and density (total number of individuals) are simultaneously manipulated with the aim to understand the roles of species neutrality vs. negative frequency-dependent coexistence mechanisms. To understand local species composition, these results can help us to get a better understanding about the ecological causes of global species distributions.

Supervisor: Prof. Erik Svensson
MasterĀ“s Degree Project, 60 ECTS credits, in Animal Ecology, winter 2015
Department of Biology, Lund University. (Less)
Please use this url to cite or link to this publication:
author
Rivas, Anais
supervisor
organization
course
BIOP01 20142
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
5152954
date added to LUP
2015-03-10 15:29:34
date last changed
2015-03-10 15:29:34
@misc{5152954,
  abstract     = {Closely related species often share the same local environment and use similar resources. Local diversity could then be maintained through some frequency-dependent species maintenance mechanism, fulfilling the invasibility criterion. Alternatively, and according to the neutral theory of biodiversity, different species should randomly go extinct over time. Here, I studied two closely related and congeneric damselfly species (Calopteryx splendens and Calopteryx virgo) to investigate if, how and why species with similar ecology could coexist. Through an experimental investigation in large outdoor cages, I investigated if there was any evidence for either species neutrality or coexistence via negative frequency dependent survival advantages of rare species. I quantified the longevity of both species under several different density and frequency treatments, where the number and species composition in the cages was manipulated in a fully factorial experimental design. My results suggest that longevity of these two species was similar over a large range of densities and frequency treatments, except when total male density was low and the frequency of C. splendens males was high. In this situation, C. virgo males showed evidence of a negative frequency-dependent survival advantage. I also present data on species-specific territoriality and discuss how territorial plasticity might contribute to coexistence between the two species. I found that C. virgo was significantly more likely to be territorial in two out of six density -and frequency treatments than was C. splendens. Overall, my results are consistent with species neutrality across most density and frequency-environments, although there is also evidence for negative frequency dependent fitness advantage of C. virgo at low density and when C. splendens was common. Therefore, different outcomes would be expected when these two ecologically similar and congeneric damselflies come in to contact with each other in nature, depending on environmental context.},
  author       = {Rivas, Anais},
  language     = {eng},
  note         = {Student Paper},
  title        = {Co-existence of calopterygid damselfly species: neutrality or negative frequency dependence?},
  year         = {2015},
}