Stress intensity and fitness in the parasitoid Aphidius ervi (Hymenoptera: Braconidae): temperature below the development threshold combined with a fluctuating thermal regime is a must

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Inclusive fitness in human relationships

For Homo sapiens , inclusive fitness theory goes well beyond 'kin'. As William Hamilton hypothesized, genes can increase the probability of their own survival by bringing about the reproduction of not only family members with whom they share copies, but also of any individuals with whom they share copies. Research with Hamilton's theory on people is less well known and remains controversial. This review shows: (1) spouses and close friends assort on blood groups and that similarity predicts fertility; (2) twin and adoption studies find genes rather than upbringing cause people to positively assort; (3) phenotype matching is more pronounced on more heritable items within sets of homogeneous traits; (4) bereavement studies find grief is greater following the death of a more similar co-twin or child; (5) studies of face perception find people prefer and trust those who look like them; and (6) DNA variance within and between ethnic groups is equivalent to that within and between families.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 8–12.     

Changes in satellite‐derived vegetation growth trend in temperate and boreal Eurasia from 1982 to 2006

Monitoring changes in vegetation growth has been the subject of considerable research during the past several decades, because of the important role of vegetation in regulating the terrestrial carbon cycle and the climate system. In this study, we combined datasets of satellite‐derived Normalized Difference Vegetation Index (NDVI) and climatic factors to analyze spatio‐temporal patterns of changes in vegetation growth and their linkage with changes in temperature and precipitation in temperate and boreal regions of Eurasia (> 23.5°N) from 1982 to 2006. At the continental scale, although a statistically significant positive trend of average growing season NDVI is observed (0.5 × 10^?3 year^?1, P = 0.03) during the entire study period, there are two distinct periods with opposite trends in growing season NDVI. Growing season NDVI has first significantly increased from 1982 to 1997 (1.8 × 10^?3 year^?1, P < 0.001), and then decreased from 1997 to 2006 (?1.3 × 10^?3 year^?1, P = 0.055). This reversal in the growing season NDVI trends over Eurasia are largely contributed by spring and summer NDVI changes. Both spring and summer NDVI significantly increased from 1982 to 1997 (2.1 × 10^?3 year^?1, P = 0.01; 1.6 × 10^?3 year^?1P < 0.001, respectively), but then decreased from 1997 to 2006, particularly summer NDVI which may be related to the remarkable decrease in summer precipitation (?2.7 mm yr^?1, P = 0.009). Further spatial analyses supports the idea that the vegetation greening trend in spring and summer that occurred during the earlier study period 1982–1997 was either stalled or reversed during the following study period 1997–2006. But the turning point of vegetation NDVI is found to vary across different regions.     

Thermal tolerance of sympatric hymenopteran parasitoid species: does it match seasonal activity?

Climatic changes result in an increased in mean temperature and in a higher incidence of extreme weather events such as heat and cold waves. For ectotherms, such as insect parasitoids, the ability to remain active under extreme climatic conditions is a significant key to fitness. The body size of individuals, and in particular their surface to volume ratio, may play a role in their resistance to thermal conditions. The thermal tolerances are investigated of two closely‐related sympatric parasitoid species [Aphidius avenae Haliday and Aphidius rhopalosiphi De Stefani‐Perez (Hymenoptera: Aphidiinae)] that have a similar ecology but differ in body size and phenologies. The critical thermal limits of individuals are assessed in both sexes of each parasitoid species and the influence of surface–volume ratios on their thermal tolerances. Aphidius avenae is less resistant to low temperatures and more resistant to high temperatures than A. rhopalosiphi. The lower surface to volume ratio of A. avenae individuals may help them to remain active in summer when experiencing heat waves. However, body size is not the sole factor that plays a role in differences of thermal tolerance between species and body size may not be an adaptation to extreme temperatures but rather a by‐product of developmental regulation. Closely‐related sympatric species from the same ecological guild can have different thermal tolerances that may allow them to occur within the same habitat. The present study also highlights the importance of clearly defining how to measure critical thermal limits to determine the thermal tolerance of a species.     

Assessing the magnitude of species richness in tropical marine environments: exceptionally high numbers of molluscs at a New Caledonia site

Earlier studies in the tropical Indo-Pacific have grossly underestimated the richness of macrofauna species at spatial scales relevant to conservation and management as a result of insufficient collecting and sorting effort. A massive collecting effort involving 400 day-persons at 42 discrete stations on a 295-km² site on the west coast of New Caledonia, south-west Pacific, revealed 2738 species of marine molluscs. This is several times the number of species recorded from any area of comparable extension anywhere in the world. Spatial and habitat heterogeneity is high with 32% of the species collected at a single station. With 20% of the species represented by single specimens (0.4% of all catches), rare species make up a considerable proportion of the fauna. This justifies the parallel drawn between coral reefs and rain forests in terms of species diversity. The real richness of many soft-bodied marine taxa is probably underestimated, as evidenced by the fact that 28.5% of the mollusc species present at the study site are represented in the samples only by empty shells. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 75 , 421–436.     

Reproductive system,social organization,human disturbance and ecological dominance in native populations of the little fire ant,Wasmannia auropunctata

The invasive ant species Wasmannia auropunctata displays both ecologically dominant and non‐dominant populations within its native range. Three factors could theoretically explain the ecological dominance of some native populations of W. auropunctata: (i) its clonal reproductive system, through demographic and/or adaptive advantages; (ii) its unicolonial social organization, through lower intraspecific and efficient interspecific competition; (iii) the human disturbance of its native range, through the modification of biotic and abiotic environmental conditions. We used microsatellite markers and behavioural tests to uncover the reproductive modes and social organization of dominant and non‐dominant native populations in natural and human‐modified habitats. Microsatellite and mtDNA data indicated that dominant and non‐dominant native populations (supercolonies as determined by aggression tests) of W. auropunctata did not belong to different evolutionary units. We found that the reproductive system and the social organization are neither necessary nor sufficient to explain W. auropunctata ecological dominance. Dominance rather seems to be set off by unknown ecological factors altered by human activities, as all dominant populations were recorded in human‐modified habitats. The clonal reproductive system found in some populations of W. auropunctata may however indirectly contribute to its ecological dominance by allowing the species to expand its environmental niche, through the fixation over time of specific combinations of divergent male and female genotypes. Unicoloniality may rather promote the range expansion of already dominant populations than actually trigger ecological dominance. The W. auropunctata model illustrates the strong impact of human disturbance on species’ ecological features and the adaptive potential of clonal reproductive systems.