Is colour polymorphism advantageous to populations and species?

I am writing in response to an article by Bolton, Rollins and Griffith (2015) entitled ‘The danger within: the role of genetic, behavioural and ecological factors in population persistence of colour polymorphic species’ that was recently published as an Opinion under the NEWS AND VIEWS section in Molecular Ecology. Bolton et al. (Molecular Ecology, 2015, 24 , 2907) argue that colour polymorphism may reduce population fitness and increase extinction risk and emphasize that this is contrary to predictions put forward by Forsman et al. (Ecology, 89 , 2008, 34) and Wennersten & Forsman (Biological Reviews 87 , 2012, 756) that the existence of multiple colour morphs with co‐adapted gene complexes and associated trait values may increase the ecological and evolutionary success of polymorphic populations and species. Bolton et al. (Molecular Ecology, 2015, 24 , 2907) further state that there is no clear evidence from studies of ‘true polymorphic species’ that polymorphism promotes population persistence. In response, I (i) challenge their classifications of polymorphisms and revisit the traditional definitions recognizing the dynamic nature of polymorphisms, (ii) review empirical studies that have examined whether and how polymorphism is associated with extinction risk, (iii) discuss the roles of trait correlations between colour pattern and other phenotypic dimensions for population fitness and (iv) highlight that the causes and mechanisms that influence the composition and maintenance of polymorphisms are different from the consequences of the polymorphic condition and how it may impact on aspects of ecological success and long‐term persistence of populations and species.     

A finite element analysis of masticatory stress hypotheses

Understanding how the skull transmits and dissipates forces during feeding provides insights into the selective pressures that may have driven the evolution of primate skull morphology. Traditionally, researchers have interpreted masticatory biomechanics in terms of simple global loading regimes applied to simple shapes (i.e., bending in sagittal and frontal planes, dorsoventral shear, and torsion of beams and cylinders). This study uses finite element analysis to examine the extent to which these geometric models provide accurate strain predictions in the face and evaluate whether simple global loading regimes predict strains that approximate the craniofacial deformation pattern observed during mastication. Loading regimes, including those simulating peak loads during molar chewing and those approximating the global loading regimes, were applied to a previously validated finite element model (FEM) of a macaque (Macaca fascicularis) skull, and the resulting strain patterns were compared. When simple global loading regimes are applied to the FEM, the resulting strains do not match those predicted by simple geometric models, suggesting that these models fail to generate accurate predictions of facial strain. Of the four loading regimes tested, bending in the frontal plane most closely approximates strain patterns in the circumorbital region and lateral face, apparently due to masseter muscle forces acting on the zygomatic arches. However, these results indicate that no single simple global loading regime satisfactorily accounts for the strain pattern found in the validated FEM. Instead, we propose that FE models replace simple cranial models when interpreting bone strain data and formulating hypotheses about craniofacial biomechanics.     

白纹伊蚊实验种群动态的研究

在实验室条件下观察白纹伊蚊种群发育、存活和繁殖的动态,得出年龄特征存活率、繁殖率等数据,编制成生命表,计算出有关种群各项参数,包括内禀增长能力(r_m=0.1333),净增殖率(R₀=45.3017),增殖有限速率(λ=1.1426),平均世代周期长(T=33.3299天),瞬时出生率和死亡率(b=0.5562,d=0.4229),稳定年龄组配,成虫前期占90.66%,成虫期占9.34%。该蚊种群大约每隔5.2天增加一倍。根据结果对该蚊种群传播登革热的关系和防制加以讨论。     

Population Density and Spatial Pattern of Heterodera glycines in Relation to Soybean Phenology

Population dynamics of Heterodera glycines (SCN) were influenced by initial nematode population density in soil, soybean root growth pattern, soil type, and environmental conditions in two field experiments. Low initial populations (Pi) of SCN increased more rapidly during the growing season than high Pi and resulted in greater numbers of nematodes at harvest. Egg and juvenile (J2) populations increased within 2-6 weeks after planting when early-season soil temperatures were 20 C and above and were delayed by soil temperatures of 17 C or below in May and early June. Frequencies of occurrence and number of nematodes decreased with increasing depth and distance from center of the soybean row. Spatial pattern of SCN paralleled that of soybean roots. Higher clay content in the subsoil 30-45 cm deep in one field restricted soil penetration by roots, indirectly influencing vertical distribution of SCN. Shoot dry weight was a good indicator of the effect of SCN on seed yield. Root dry weight was poorly correlated with soybean growth and yield. The relationship of yield (seed weight) to Pi was best described by a quadratic equation at one site, but did not fit any regression model tested at the second site.     

中国桃蛀螟不同地理种群的遗传多样性

本文应用ISSR分子标记技术对中国桃蛀螟Conogethes punctiferalis 11个地理种群的基因组DNA进行了遗传多样性和遗传分化分析。从34条引物中筛选出6条用于ISSR多态性分析, 共扩增出211条带, 其中209条具多态性, 总的多态性条带百分率为99.05%。11个种群的遗传距离在0.0059~0.0237之间, Nei氏基因多样性指数为0.1750, Shannon信息指数为0.2966, 遗传分化系数为0.053, 基因流高达8.8724。结果提示中国桃蛀螟地理种群因基因流水平较高而种群遗传分化水平保持较低。     

Bumble bee colony dynamics: quantifying the importance of land use and floral resources for colony growth and queen production

Bumble bee (Bombus) species are ecologically and economically important pollinators, and many species are in decline. In this article, we develop a mechanistic model to analyse growth trajectories of Bombus vosnesenskii colonies in relation to floral resources and land use. Queen production increased with floral resources and was higher in semi‐natural areas than on conventional farms. However, the most important parameter for queen production was the colony growth rate per flower, as opposed to the average number of available flowers. This result indicates the importance of understanding mechanisms of colony growth, in order to predict queen production and enhance bumble bee population viability. Our work highlights the importance of interpreting bumble bee conservation efforts in the context of overall population dynamics and provides a framework for doing so.     

Seed germination and antioxidant pattern in Lavandula multifida (Lamiaceae): A comparison between core and peripheral populations

We evaluated the environmental adaptability of Lavandula multifida L., a plant species presents in the Western Mediterranean Basin with a threatened peripheral population in Southern Italy. Germination capacity, activities of some hydrolyzing enzymes associated with germination and antioxidative pathway of Calabrian L. multifida were quantified in comparison with a Spanish core population. The Calabrian population showed a lower germination ability and it can be related to the small size of the population and associated inbreeding depression. Difference between two populations in enzymatic assays and antioxidative pattern during germination and early seedling development may in part explain a different ability of these two populations to respond to external cues and a diverse environmental adaptability. The study on germination strategies of isolated populations is important to define possible programmes to preserve genetic biodiversity of autochthon plants populations.     

Projecting the future of an alpine ungulate under climate change scenarios

Climate change represents a primary threat to species persistence and biodiversity at a global scale. Cold adapted alpine species are especially sensitive to climate change and can offer key “early warning signs” about deleterious effects of predicted change. Among mountain ungulates, survival, a key determinant of demographic performance, may be influenced by future climate in complex, and possibly opposing ways. Demographic data collected from 447 mountain goats in 10 coastal Alaska, USA, populations over a 37‐year time span indicated that survival is highest during low snowfall winters and cool summers. However, general circulation models (GCMs) predict future increase in summer temperature and decline in winter snowfall. To disentangle how these opposing climate‐driven effects influence mountain goat populations, we developed an age‐structured population model to project mountain goat population trajectories for 10 different GCM/emissions scenarios relevant for coastal Alaska. Projected increases in summer temperature had stronger negative effects on population trajectories than the positive demographic effects of reduced winter snowfall. In 5 of the 10 GCM/representative concentration pathway (RCP) scenarios, the net effect of projected climate change was extinction over a 70‐year time window (2015–2085); smaller initial populations were more likely to go extinct faster than larger populations. Using a resource selection modeling approach, we determined that distributional shifts to higher elevation (i.e., “thermoneutral”) summer range was unlikely to be a viable behavioral adaptation strategy; due to the conical shape of mountains, summer range was expected to decline by 17%–86% for 7 of the 10 GCM/RCP scenarios. Projected declines of mountain goat populations are driven by climate‐linked bottom‐up mechanisms and may have wide ranging implications for alpine ecosystems. These analyses elucidate how projected climate change can negatively alter population dynamics of a sentinel alpine species and provide insight into how demographic modeling can be used to assess risk to species persistence.