Hormonal mechanisms underlie many life-history traits and their interactions. We studied the role of ecdysteroids with regard to wing pattern and development time of the polyphenic butterfly Bicyclus anynana. Ecdysteroid titers and sensitivity to ecdysone injection were assayed for two-trait selected lines (ventral eyespot size and development time concurrently). These two traits are genetically and phenotypically coupled, having a common endocrinal basis. Two-trait selection had been applied both antagonistically (opposite the correlation) and synergistically (in the same direction as the correlation). Although selected lines had diverged most in eyespot size, the widest differences in timing of ecdysteroid titers were observed between the development time selection regimes; fast selected lines had an earlier hormonal increase after pupation than slow selected lines (even when corrected for differential pupal times). This endocrine peak was also earlier for females than for males. Furthermore, sensitivity to ecdysone injection as measured by a subsequent decrease in pupal time was significantly lower for slow selected lines than for fast or unselected lines. We conclude that the observed response in eyespot size to artificial selection must have been achieved via alteration of, or selection on, other developmental mechanisms, because the dynamics of the alternative, hormonal, pathway were dictated by development time selection. The developmental system is flexible enough to allow evolution in directions opposing the correlation between wing pattern and developmental time, and responses to selection are not constrained by a shared hormonal system.
We investigated the effects of inbreeding on various fitness components and their genetic load in laboratory metapopulations of the butterfly Bicyclus anynana. Six metapopulations each consisted of four subpopulations with breeding population sizes of N ϭ 6 or N ϭ 12 and migration rate of m ϭ 0 or m ϭ 0.33. Metapopulations were maintained for seven generations during which coancestries and pedigrees were established. Individual inbreeding coefficients at the F 7 were calculated and ranged between 0.01 and 0.51. Even though considerable purging had occurred during inbreeding, the genetic load remained higher than that of many outbreeding species: approximately two lethal equivalents were detected for egg sterility, one for zygote survival, one for juvenile survival, and one for longevity. Severe inbreeding depression occurred after seven generations of inbreeding, which jeopardized the metapopulation survival. This finding suggests that the purging of genetic load by intentional inbreeding cannot be recommended for the genetic conservation of species with a high number of lethal equivalents.
Decision transparency is often proposed as a way to maintain or even increase citizen trust, yet this assumption is still untested in the context of regulatory agencies. We test the effect of transparency of a typical decision tradeoff in regulatory enforcement: granting forbearance or imposing a sanction. We employed a representative survey experiment (n = 1,546) in which we test the effect of transparency in general (providing information about a decision or not) and the effect of specific types of transparency (process or rationale transparency). We do this for agencies supervising financial markets, education, and health care. We find that overall decision transparency significantly increases citizen trust in only two of the three agencies. Rationale transparency has a more pronounced positive effect only for the Education Inspectorate. We conclude that the overall effect of decision transparency is positive but that the nature of the regulatory domain may weaken or strengthen this effect.
Theory about the role of constraints in evolution is abundant, but few empirical data exist to describe the consequences a bias in phenotypic variation has for micro evolution. Responses to natural selection can be severely hampered by a genetic correlation among a suite of traits. Constraints can be studied using antagonistic selection experiments, that is, two-trait selection in opposition to this correlation. The two traits studied here were development time and wing pattern (eyespot size) in the butterfly Bicyclus anynana, both of which have a clear adaptive significance. Rates of response were higher for eyespot size than for development time, but were independent of the concurrent selection (either in the same direction as the correlation or perpendicular to it). Regimes differed in both traits in all directions after 11 generations of selection. The uncoupling lines had higher relative responses than the synergistic lines in development time and equal relative responses in eyespot size. The patterns for eyespot size (reaction norms) were consistent across different rearing temperatures. Differences in lines selected for fast and slow development time were more pronounced at lower temperatures, irrespective of the direction of joint wing pattern selection. Furthermore, correlated responses in pupal weight and growth rate were observed; lines selected for a slower development had higher pupal weights, especially at lower temperatures. The response of the uncoupling lines was not hampered by a lack of selectable genetic variation, and the relative response in the development time was larger than expected based on response in the coupled direction and quantitative genetic predictions. This suggests that the structure of the genetic architecture does not constrain the short-term, independent evolution of both wing pattern and development time.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.