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Costly sexual ornaments coevolve with fast life-histories in killifishes
Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.ORCID-id: 0000-0002-3705-1907
Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.ORCID-id: 0000-0002-7247-3742
Visa övriga samt affilieringar
(Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
Abstract [en]

Sexually selected ornaments constitute an important investment into reproduction, increasing current mating success, at a potential cost to survival. Theory suggests that exaggerated sexual ornaments may coevolve with the life-history trade-off between current and future reproduction, however this hypothesis has remained unexplored. Here, we determine how the size of secondary sexual traits coevolves with the pace of life-histories (slow or fast), using a clade of killifishes, where independent adaptations to ephemeral environments have resulted in substantial divergences in life-history strategy. In addition, we assess costs to swimming performance driven by enlarged, ornamental fins. We predict that killifishes with fast life-histories, which inhabit time-limited environments and prioritize current reproduction, will have a greater tendency to evolve enlarged fins, compared to killifishes with slow life-histories. Indeed, we found that species with fast life-histories had more pronounced sexual size dimorphism, with males from these species having exaggerated dorsal and anal fins, compared to species with slow life-histories. Furthermore, males from species with fast life-histories and larger ornaments exhibited lower swimming performances compared to both conspecific females, and individuals from species with slow life-histories. Our results indicate that the trade-off between current and future reproduction, can be an evolutionary driver of costly sexual ornaments.

Nyckelord [en]
fins, fish, life-history theory, sexual selection, secondary sexual traits
Nationell ämneskategori
Evolutionsbiologi
Forskningsämne
etologi
Identifikatorer
URN: urn:nbn:se:su:diva-169671OAI: oai:DiVA.org:su-169671DiVA, id: diva2:1324081
Tillgänglig från: 2019-06-13 Skapad: 2019-06-13 Senast uppdaterad: 2019-12-17Bibliografiskt granskad
Ingår i avhandling
1. Behavioural, physiological and morphological correlates of life-history in killifishes − a macroevolutionary approach
Öppna denna publikation i ny flik eller fönster >>Behavioural, physiological and morphological correlates of life-history in killifishes − a macroevolutionary approach
2019 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Life-histories commonly evolve along a continuum from short-lived and fecund, to long-lived and less fecund. Because life-history traits are mostly components of reproduction and survival, understanding the causes and consequences of life-history variation is at the core of evolutionary biology. This thesis aims to identify what other key traits (e.g. behavioural, physiological and morphological traits) covary with life-history, and why. Numerous hypotheses describe how life-history might be associated with other traits, with life-history trade-offs often considered to be a primary driver of any such relationships. For example, since resources are limited, increased investment in one trait must lead to decreased investment in one or several other traits, all else equal. Hypotheses on the relationship between life-history and other traits have been tested in many studies, but empirical studies in controlled experimental settings are rare. In this thesis I explore how behaviour, physiology and morphology relate to variation along the life-history continuum from fast to slow, in a system with substantial variation in life-history traits - the killifishes.

I began by exploring the patterns of egg to body size allometry in killifishes (Paper I), where species with faster life-histories showed indications of constraints on the independent evolution of egg size and body size. Furthermore, I found evidence of differences in variance and in the rates of evolution of egg size and body size across species, potentially caused by the colonisation of ephemeral habitats, which could have selected for adaptations that lead to differences in size.

I then performed a comparative common garden study (Paper II) of the pace-of-life syndrome hypothesis, which predicts that species with fast life-histories should take larger risks in order to maintain their increased reproductive rate. I obtained data on risk taking behaviours, including movement, tendency to enter an open environment, and aggressiveness, in addition to metabolic rate, for 20 species of killifish, with multiple replicates per species. The results indicated trait dependent associations with life-history, where aggression seemed to correlate positively with speed of life-history, in congruence with our prediction.

Next, my colleagues and I assessed the association between life-history and sexual selection (Paper III), in order to determine if investment in secondary sexual traits might be traded off against survival in killifish. Fin size was found to be negatively associated with escape performance in a simulated predator attack, suggesting survival costs for individuals with large fins. Importantly, fin size was also positively associated with the speed of life-history, supporting the hypothesis that costs to survival probability is lower in fast-living species.

Lastly, I tested the hypothesized negative covariation between relative brain size and speed of life-history, by collecting and analysing brain size measurements for 21 species of killifish (Paper IV). Surprisingly, a positive relationship between speed of life-history and relative brain size was found for adults, although juveniles did not differ in relative brain size. This implies at least one of two things: either there is no need to trade off brain size with life-history since resource acquisition is higher, or brain size and life-history are traded-off with other traits.

In conclusion, I show that previously found trade-offs between life-history and investment in other costly traits are only sometimes present, when tested in a system with substantial divergences in the speed of life-history. I also provide evidence for a trait dependent association between life-history and among species differences in risk-taking and metabolic rate.

Ort, förlag, år, upplaga, sidor
Stockholm: Department of Zoology, Stockholm University, 2019. s. 19
Nyckelord
brain size evolution, comparative analysis, life-history continuum, risk-taking behaviour, sexual selection, trade-offs
Nationell ämneskategori
Etologi
Forskningsämne
etologi
Identifikatorer
urn:nbn:se:su:diva-169666 (URN)978-91-7797-759-9 (ISBN)978-91-7797-760-5 (ISBN)
Disputation
2019-09-06, Vivi Täckholmsalen (Q-salen), NPQ-huset, Svante Arrhenius väg 20, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Forskningsfinansiär
Vetenskapsrådet
Anmärkning

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. 4: Manuscript.

Tillgänglig från: 2019-08-14 Skapad: 2019-06-13 Senast uppdaterad: 2019-08-19Bibliografiskt granskad

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Eckerström-Liedholm, SimonRowiński, PiotrGonzalez-Voyer, AlejandroRogell, Björn
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Zoologiska institutionen
Evolutionsbiologi

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