| 1. |
- Gonzalez-Voyer, Alejandro, et al.
(författare)
-
Larger brain size indirectly increases vulnerability to extinction in mammals
- 2016
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 70:6, s. 1364-1375
-
Tidskriftsartikel (refereegranskat)abstract
- Although previous studies have addressed the question of why large brains evolved, we have limited understanding of potential beneficial or detrimental effects of enlarged brain size in the face of current threats. Using novel phylogenetic path analysis, we evaluated how brain size directly and indirectly, via its effects on life history and ecology, influences vulnerability to extinction across 474 mammalian species. We found that larger brains, controlling for body size, indirectly increase vulnerability to extinction by extending the gestation period, increasing weaning age, and limiting litter sizes. However, we found no evidence of direct, beneficial, or detrimental effects of brain size on vulnerability to extinction, even when we explicitly considered the different types of threats that lead to vulnerability. Order-specific analyses revealed qualitatively similar patterns for Carnivora and Artiodactyla. Interestingly, for Primates, we found that larger brain size was directly (and indirectly) associated with increased vulnerability to extinction. Our results indicate that under current conditions, the constraints on life history imposed by large brains outweigh the potential benefits, undermining the resilience of the studied mammals. Contrary to the selective forces that have favored increased brain size throughout evolutionary history, at present, larger brains have become a burden for mammals.
|
|
| 2. |
- Dugo-Cota, Alvaro, et al.
(författare)
-
A test of the integrated evolutionary speed hypothesis in a Neotropical amphibian radiation
- 2015
-
Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 24:7, s. 804-813
-
Tidskriftsartikel (refereegranskat)abstract
- Aim - The evolutionary speed hypothesis is a mechanistic explanation for the latitudinal biodiversity gradient. The recently extended integrated evolutionary speed hypothesis (IESH) proposes that temperature, water availability, population size and spatial heterogeneity influence the rate of molecular evolution which, in turn, affects diversification. However, the evidence for some of the associations predicted by the IESH is not conclusive, and in some cases is contradictory.Location - The Neotropics.Methods - Using a comparative Bayesian method we tested the following predictions of the IESH: the association between the rate of molecular evolution and temperature (and elevation and latitude, as proxies), water availability (using precipitation and relative humidity as proxies), productivity and rate of diversification. We also accounted for the potential confounding effects of body size and UVB radiation. We tested these predictions separately in mitochondrial and nuclear genes.Results - Substitution rates of mitochondrial and nuclear genes were positively associated with temperature and negatively with elevation, while only the mitochondrial coding gene rate was associated with UVB radiation. However, when controlling for temperature, the association between substitution rate and elevation and UVB radiation disappeared, while a negative association with precipitation emerged. Moreover, diversification events were positively correlated with the rate of molecular evolution but only in mitochondrial genes.Main conclusions - Our results support two key predictions of the IESH. They highlight the important association between rate of molecular evolution and temperature within a recently diverged group and also confirm the positive association between molecular evolution and diversification rate, although only in mitochondrial genes. However, the lack of association between diversification and temperature and the low effect size of the relationship between substitution rates and diversification in mitochondrial genes emphasize the important role other factors, such as time, spatial heterogeneity and population size might have in the origin and maintenance of the latitudinal biodiversity gradient.
|
|
| 3. |
- Eckerström-Liedholm, Simon, 1988-
(författare)
-
Behavioural, physiological and morphological correlates of life-history in killifishes − a macroevolutionary approach
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
|
|
| 4. |
- Eckerström-Liedholm, Simon, et al.
(författare)
-
Macroevolutionary evidence suggests trait-dependent coevolution between behavior and life-history
- 2019
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 73:11, s. 2312-2323
-
Tidskriftsartikel (refereegranskat)abstract
- Species with fast life-histories typically prioritize current over future reproductive events, compared to species with slow life-histories. These species therefore require greater energetic input into reproduction, and also likely have less time to realize their reproductive potential. Hence, behaviors that increase access to both resources and mating opportunities, at a cost of increased mortality risk, could coevolve with the pace of life-history. However, whether this prediction holds across species, remains untested under standardized conditions. Here, we test how risky behaviors, which facilitate access to resources and mating opportunities (i.e., activity, boldness, and aggression), along with metabolic rate, coevolve with the pace of life-history across 20 species of killifish that present remarkable divergences in the pace of life-history. We found a positive association between the pace of life-history and aggression, but interestingly not with other behavioral traits or metabolic rate. Aggression is linked to interference competition, and in killifishes is often employed to secure mates, while activity and boldness are more relevant for exploiting energetic resources. Our results suggest that the trade-off between current and future reproduction plays a more prominent role in shaping mating behavior, while behaviors related to energy acquisition may be influenced by ecological factors.
|
|
| 5. |
- Eckerström-Liedholm, Simon, et al.
(författare)
-
Time-limited environments affect the evolution of egg-body size allometry
- 2017
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 71:7, s. 1900-1910
-
Tidskriftsartikel (refereegranskat)abstract
- Initial offspring size is a fundamental component of absolute growth rate, where large offspring will reach a given adult body size faster than smaller offspring. Yet, our knowledge regarding the coevolution between offspring and adult size is limited. In time-constrained environments, organisms need to reproduce at a high rate and reach a reproductive size quickly. To rapidly attain a large adult body size, we hypothesize that, in seasonal habitats, large species are bound to having a large initial size, and consequently, the evolution of egg size will be tightly matched to that of body size, compared to less time-limited systems. We tested this hypothesis in killifishes, and found a significantly steeper allometric relationship between egg and body sizes in annual, compared to nonannual species. We also found higher rates of evolution of egg and body size in annual compared to nonannual species. Our results suggest that time-constrained environments impose strong selection on rapidly reaching a species-specific body size, and reproduce at a high rate, which in turn imposes constraints on the evolution of egg sizes. In combination, these distinct selection pressures result in different relationships between egg and body size among species in time-constrained versus permanent habitats.
|
|
| 6. |
- Rodríguez, Ariel, et al.
(författare)
-
Cryptic within cryptic : genetics, morphometrics, and bioacoustics delimitate a new species of Eleutherodactylus (Anura: Eleutherodactylidae) from Eastern Cuba
- 2017
-
Ingår i: Zootaxa. - : Magnolia Press. - 1175-5326 .- 1175-5334. ; 4221:5, s. 501-522
-
Tidskriftsartikel (refereegranskat)abstract
- We studied the variation in genetics, bioacustics, and morphology in Eleutherodactylus glamyrus, a regionally endemic frog species restricted to high elevations in the Sierra Maestra Massif, Western Cuba that was originally described as a cryptic species hidden under the name E. auriculatus. Genetic analysis of mtDNA sequences of the 16S and cob genes identify two allopatric and strongly supported mitochondrial clades (phylogroups) which also showed no haplotype sharing in the nuclear Rag-1 gene. Bioacustic, and morphological comparisons concordantly identify these two phylogroups as independent evolutionary lineages. Therefore, we herein restrict the name Eleutherodactylus glamyrus Estrada and Hedges to populations represented in our analyses as the western phylogroup (Cordillera del Turquino to Pico La Bayamesa) and consider specimens from the eastern phylogroup (Sierra del Cobre) to represent a new species described and named as Eleutherodactylus cattus. Our results add to the growing list of Eleutherodactylus species endemic to Cuba and highlight the importance of combining different sources of evidence for obtaining robust assessments of species limits in amphibians.
|
|
| 7. |
- Sol, Daniel, et al.
(författare)
-
Risk-taking behavior, urbanization and the pace of life in birds
- 2018
-
Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 72:3
-
Tidskriftsartikel (refereegranskat)abstract
- Despite growing appreciation of the importance of considering a pace-of-life syndrome (POLS) perspective to understand how animals interact with their environment, studies relating behavior to life history under altered environmental conditions are still rare. By means of a comparative analysis of flight initiation distances (i.e., the distance at which an animal takes flight when a human being is approaching) across > 300 bird species distributed worldwide, we document here the existence of a POLS predicted by theory where slow-lived species tend to be more risk-averse than fast-lived species. This syndrome largely emerges from the influence of body mass, and is highly dependent on the environmental context. Accordingly, the POLS structure vanishes in urbanized environments due to slow-lived species adjusting their flight distances based on the perception of risk. While it is unclear whether changes in POLS reflect plastic and/or evolutionary adjustments, our findings highlight the need to integrate behavior into life history theory to fully understand how animals tolerate human-induced environmental changes. Significance statement Animals can often respond to changing environmental conditions by adjusting their behavior. However, the degree to which different species can modify their behavior depends on their life history strategy and on the environmental context. Species-specific perception of risk is a conspicuous example of adjustable behavior tightly associated with life history strategy. While there is a general tendency of higher risk aversion in rural than city-dwelling birds, it is dependent on the species' life history strategy. Slow-lived species are more prone to adjust their flight initiation distances based on the perception of risk, allowing humans to approach closer in urban than rural environments. Behavior must therefore be taken into account together with life history to reliably assess species' vulnerability at the face of ongoing environmental change.
|
|
| 8. |
- Tsuboi, Masahito, et al.
(författare)
-
Functional coupling constrains craniofacial diversification in Lake Tanganyika cichlids
- 2015
-
Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 11:5
-
Tidskriftsartikel (refereegranskat)abstract
- Functional coupling, where a singlemorphological trait performs multiple functions, is a universal feature of organismal design. Theory suggests that functional coupling may constrain the rate of phenotypic evolution, yet empirical tests of this hypothesis are rare. In fish, the evolutionary transition from guarding the eggs on a sandy/rocky substrate (i.e. substrate guarding) to mouthbrooding introduces a novel function to the craniofacial system and offers an ideal opportunity to test the functional coupling hypothesis. Using a combination of geometric morphometrics and a recently developed phylogenetic comparative method, we found that head morphology evolution was 43% faster in substrate guarding species than in mouthbrooding species. Furthermore, for species in which females were solely responsible for mouthbrooding the males had a higher rate of head morphology evolution than in those with biparental mouthbrooding. Our results support the hypothesis that adaptations resulting in functional coupling constrain phenotypic evolution.
|
|
