Domestication and fitness in the wild: A multivariate view

Domesticated species continually escaping and interbreeding with wild relatives impose a migration load on wild populations. As domesticated stocks become increasingly different as a result of artificial and natural selection in captivity, fitness of escapees in the wild is expected to decline, reducing the effective rate of migration into wild populations. Recent theory suggest that this may alleviate and eventually eliminate the resulting migration load. I develop a multivariate model of trait and wild fitness evolution resulting from the joint effects of artificial and natural selection in the captive environment. Initially, the evolutionary trajectory is dominated by the effects of artificial selection causing a fast initial decline in fitness of escapees in the wild. In later phases, through the counteracting effects of correlational multivariate natural selection in captivity, the mean phenotype is pushed in directions of weak stabilizing selection, allowing a sustained response in the trait subject to artificial selection. Provided that there is some alignment between the adaptive landscapes in the wild and in captivity, these phases are associated with slower rates of decline in wild fitness of the domesticated stock, suggesting that detrimental effects on wild populations are likely to remain a concern in the foreseeable future.     

Cannibalism and protective behavior of eggs in Arctic charr (Salvelinus alpinus)

From video recordings of spawning events, we quantified protective and cannibalistic behavior of Arctic charr occurring immediately after spawning. The number of fish cannibalizing on stray eggs was examined regarding (a) whether more than one male shed milt during the spawning event, that is, whether sperm competition occurred, (b) whether the sperm competition included few or many males, that is, the intensity of sperm competition, and (c) the density of fish at the spawning site. Response behavior toward egg cannibalism was also examined among females and dominant males in order to determine any parental investment toward protecting the eggs after spawning. Cannibalistic behavior was seen in almost 50% of the spawnings, and the multiple spawning events showed the highest numbers of fish cannibalizing on eggs. Both the number of males releasing milt and the number of fish approaching the spawning site were positively correlated with egg cannibalism. Sperm competition was, however, not a prerequisite for egg cannibalism. Although we also observed partial filial cannibalism, protective behavior of eggs was seen both among dominant males and females, suggesting that charr actually conduct parental care.     

The wound inflammatory response exacerbates growth of pre‐neoplastic cells and progression to cancer

There is a long‐standing association between wound healing and cancer, with cancer often described as a “wound that does not heal”. However, little is known about how wounding, such as following surgery, biopsy collection or ulceration, might impact on cancer progression. Here, we use a translucent zebrafish larval model of Ras^G12V‐driven neoplasia to image the interactions between inflammatory cells drawn to a wound, and to adjacent pre‐neoplastic cells. We show that neutrophils are rapidly diverted from a wound to pre‐neoplastic cells and these interactions lead to increased proliferation of the pre‐neoplastic cells. One of the wound‐inflammation‐induced trophic signals is prostaglandin E₂ (PGE₂). In an adult model of chronic wounding in zebrafish, we show that repeated wounding with subsequent inflammation leads to a greater incidence of local melanoma formation. Our zebrafish studies led us to investigate the innate immune cell associations in ulcerated melanomas in human patients. We find a strong correlation between neutrophil presence at sites of melanoma ulceration and cell proliferation at these sites, which is associated with poor prognostic outcome.     

Genetic evolution,plasticity, and bet‐hedging as adaptive responses to temporally autocorrelated fluctuating selection: A quantitative genetic model

Adaptive responses to autocorrelated environmental fluctuations through evolution in mean reaction norm elevation and slope and an independent component of the phenotypic variance are analyzed using a quantitative genetic model. Analytic approximations expressing the mutual dependencies between all three response modes are derived and solved for the joint evolutionary outcome. Both genetic evolution in reaction norm elevation and plasticity are favored by slow temporal fluctuations, with plasticity, in the absence of microenvironmental variability, being the dominant evolutionary outcome for reasonable parameter values. For fast fluctuations, tracking of the optimal phenotype through genetic evolution and plasticity is limited. If residual fluctuations in the optimal phenotype are large and stabilizing selection is strong, selection then acts to increase the phenotypic variance (bet‐hedging adaptive). Otherwise, canalizing selection occurs. If the phenotypic variance increases with plasticity through the effect of microenvironmental variability, this shifts the joint evolutionary balance away from plasticity in favor of genetic evolution. If microenvironmental deviations experienced by each individual at the time of development and selection are correlated, however, more plasticity evolves. The adaptive significance of evolutionary fluctuations in plasticity and the phenotypic variance, transient evolution, and the validity of the analytic approximations are investigated using simulations.     

Erratum to: Fluorescence spectroscopy as a potential metabonomic tool for early detection of colorectal cancer

Fluorescence spectroscopy Excitation Emission Matrix (EEM) measurements were applied on human blood plasma samples from a case control study on colorectal cancer. Samples were collected before large bowel endoscopy and included patients with colorectal cancer or with adenomas, and from individuals with other non malignant findings or no findings (N = 308). The objective of the study was to explore the possibilities for applying fluorescence spectroscopy as a tool for detection of colorectal cancer. Parallel Factor Analysis (PARAFAC) was applied to decompose the fluorescence EEMs into estimates of the underlying fluorophores in the sample. Both the pooled score matrix from PARAFAC, holding the relative concentrations of the derived components, and the raw unfolded spectra were used as basis for discrimination models between cancer and the various controls. Both methods gave test set validated sensitivity and specificity values around 0.75 between cancer and controls, and poor discriminations between the various controls. The PARAFAC solution gave better options for analyzing the chemical mechanisms behind the discrimination, and revealed a blue shift in tryptophan emission in the cancer patients, a result that supports previous findings. The present findings show how fluorescence spectroscopy and chemometrics can help in cancer diagnostics, and with PARAFAC fluorescence spectroscopy can be a potential metabonomic tool.

     

Rapid recovery of recently overexploited winter grazing pastures for reindeer in northern Norway

During the last 25 yr, Sami reindeer husbandry in parts of Finnmarksvidda in the Norwegian Arctic has been in a critical state because of overexploitation of lichen-dominated tundra, which serves as winter forage. To better understand the ecosystem’s capabilities for recovery we investigated vegetation cover changes over a 7-yr period, starting in 1998, at 52 sites dispersed over a large area at Finnmarksvidda. Two types of plots were established: one fenced from reindeer grazing and trampling and one open for reindeer. The investigations in 2005 showed that lichen cover had had a significant and rapid increase (up to 8.6-fold per year). The cover of vascular plants, mainly dwarf shrubs, also increased significantly, while barren areas and the cover of litter decreased significantly during the period. Mean relative growth rate of lichen biomass was 0.083 ± 0.011 per year in open plots, which is considered very rapid recovery compared to previous studies. Lichen recovery was significantly faster on leeward ridges than on exposed ridges, and fencing alone did not have any significant effects on lichen recovery, but in interaction with time, fencing contributed to increasing recovery rates. The lichen heath recovery was reciprocally correlated with reindeer density. In addition, lichen recovery was probably facilitated by recent climate changes, viz. shallower snow depths which made leeward tundra and forest floor vegetation accessible for reindeer, and increased summer precipitation rates which improved growth rates. The results from this study show that in a very short time there was a transition from an overexploited depauperate vegetation and barren ground state to a flourishing lichen-dominated vegetation state, suggesting that the injuries were repairable. The vegetation transitions which have taken place in the study area are considered to be reversible with fewer persistent effects.     

Carotenoids‐based reddish pelvic spines in nonreproducing female and male sticklebacks (Gasterosteus aculeatus) – Signalling social dominance?

Conspicuous ornaments are often considered a result of evolution by sexual selection. According to the social selection hypothesis, such conspicuous traits may also evolve as badges of status associated with increased boldness or aggression toward conspecifics in conflicts about ecological resources. This study tested predictions from the social selection hypothesis to explain evolution of conspicuous red color of the pelvic spines of the three‐spine stickleback (Gasterosteus aculeatus). Wild nonreproducing sticklebacks were presented to pairs of dummies which differed at their pelvic spines, having either (i) normal‐sized gray or red pelvic spines or (ii) normal‐sized gray or large red pelvic spines. The experimental tank was illuminated by white or green light, since green light impedes the sticklebacks’ ability to detect red color. The dummies moved slowly around in circles at each end of the experimental tank. We quantified the parameters (i) which of the two dummies was visited first, (ii) time taken before the first visit to a dummy, (iii) distribution of the focal sticklebacks in the two zones close to each of the two dummies and in the neutral zone of the tank, (iv) close to which of the two dummies did the focal fish eat its first food‐piece, and (v) time spent until the first piece of food was eaten. This was carried out for 22 females and 29 males sticklebacks. The results suggested no effect of the color or size of the dummies’ pelvic spines, on none of the five behavioral parameters. Moreover, neither the color of the pelvic spines of the focal sticklebacks themselves (as opposed to redness of the dummies’ spines) nor their body length was associated with behavior toward the dummies. Thus, this study did not support predictions from the social selection hypothesis to explain evolution of red pelvic spines in sticklebacks.     

The role of nitric oxide in the cardiac effects of hydrogen peroxide

Oxidative stress mediated by hydrogen peroxide (H₂O₂) increases coronary flow (CF) in Langendorff-perfused rat hearts. We investigated the possible role of nitric oxide (NO) in H₂O₂-induced vasolidation. A dose-response study was conducted to find a concentration of H₂O₂ which increased CF without influencing left ventricular developed (LVDP) or end-diastolic (LVEDP) pressures. 80 (n = 10),100 (n = 7), 120 (n = 7),140 (n = 7),160 (n = 7), and 180 (n = 10) M H₂O₂ was infused for 10 min, followed by recovery for 50 min. 80 M H₂O₂ increased CF to a maximum of 143 ± 4 (mean ± S.E.M) percent of initial value after 15 min observation (p < 0.001 compared to buffer only), with no effect on LVDP or LVEDP. Another series of hearts were perfused with N-nitro-L-Arginine methylester (L-NAME, 1 M), methylene blue (MB, 50 M), or haemoglobin (Hb, 10 M), without (n = 7 in each) or with (n = 10 in each) 80 M H₂O₂ for 10 min. L-NAME, MB, and Hb alone increased CF, but attenuated the H₂O₂-induced increase of CF. LVDP was depressed when L-NAME, MB, or Hb were given in conjunction with 80 M H₂O₂. In summary, H₂O₂ concentration-dependently increased LVEDP and depressed LVDP. The H₂O₂-induced increase of CF was independent of concentration. Inhibition of NO synthesis, action, or soluble guanylate cyclase attenuated the H₂O₂-induced increase of CF, and depressed LVDP when given together with H₂O₂. H₂O₂ induces a NO-dependent vasodilation, and inhibition of NO is detrimental to left ventricular function after H₂O₂-mediated oxidative stress.