Microsatellite markers for the palaeotropic pioneer tree genus Macaranga (Euphorbiaceae) and their cross‐species transferability

We developed primer sequences for five polymorphic microsatellite loci in the tropical ant‐plant genus Macaranga (Euphorbiaceae). Population genetic parameters were determined on the basis of 30 individuals from each of two Macaranga species in Borneo. Allele numbers per locus ranged from three to 13. Expected and observed heterozygosities ranged from 0.160 to 0.850 and from 0.130 to 0.700, respectively. Four of the five primer pairs cross‐amplify polymorphic PCR products in a wide range of Macaranga species.     

Population demography influences climatic niche evolution: evidence from diploid American Hordeum species (Poaceae)

In this study, we explore the interplay of population demography with the evolution of ecological niches during or after speciation in Hordeum. While large populations maintain a high level of standing genetic diversity, gene flow and recombination buffers against fast alterations in ecological adaptation. Small populations harbour lower allele diversity but can more easily shift to new niches if they initially survive under changed conditions. Thus, large populations should be more conservative regarding niche changes in comparison to small populations. We used environmental niche modelling together with phylogenetic, phylogeographic and population genetic analyses to infer the correlation of population demography with changes in ecological niche dimensions in 12 diploid Hordeum species from the New World, forming four monophyletic groups. Our analyses found both shifts and conservatism in distinct niche dimensions within and among clades. Speciation due to vicariance resulted in three species with no pronounced climate niche differences, while species originating due to long‐distance dispersals or otherwise encountering genetic bottlenecks mostly revealed climate niche shifts. Niche convergence among clades indicates a niche‐filling pattern during the last 2 million years in South American Hordeum. We provide evidence that species, which did not encounter population reductions mainly showed ecoclimatic niche conservatism, while major niche shifts occurred in species which have undergone population bottlenecks. Our data allow the conclusion that population demography influences adaptation and niche shifts or conservatism in South American Hordeum species.     

Dissolved humic substances – ecological driving forces from the individual to the ecosystem level?

1. This review focuses on direct and indirect interactions between dissolved humic substances (HS) and freshwater organisms and presents novel opinions and hypotheses on their ecological significance. Despite their abundance in freshwaters, the role of HS is still inadequately understood. These substances have been considered too large to be taken up by freshwater organisms. On the contrary, here we present evidence that dissolved HS are indeed taken up and interact directly and/or indirectly with freshwater organisms. 2. We show that dissolved HS exert a mild chemical stress upon aquatic organisms in many ways; they induce molecular chaperones (stress shock proteins), induce and modulate biotransformation enzymes and modulate (mainly inhibiting) the photosynthetic release of oxygen by freshwater plants. Furthermore, they produce an oxidative stress, which may lead to membrane oxidation. HS modulate the multixenobiotic resistance activity and probably other membrane‐bound pumps. This property may lead to the increased bioaccumulation of xenobiotic chemicals. Furthermore, they can modulate the numbers of offspring in a nematode and feminise fish and amphibians. The ecological consequences of this potential remain obscure at present. HS also have the potential to act as chemical attractants (as shown with a nematode). 3. In some macrophytes and algae we show that HS interfere with photosynthesis and growth. For instance, the presence of HS suppresses cyanobacteria more than eukaryotic algae. By applying a quantitative structure activity relationship approach, we show that quinones in the HS interfere with photosynthetic electron transport. We show that even Phragmites leachate can act as a kind of phytotoxin. HS also have the potential to suppress fungal growth, as shown with the water mould Saprolegnia parasitica and force the fungus to respond by spore production. 4. In very soft, humic freshwaters, such as the Rio Negro, Brazil, HS stimulate the uptake of essential ions, such as Na and Ca, at extremely low pH (3.5–4.0) and prevent the ionoregulatory disturbance induced by acid waters, thereby enabling fish to survive in these environments. 5. We discuss whether or not HS are directly utilised by aquatic microorganisms or via exoenzymes, which may be washed in from the terrestrial catchment. There is accumulating evidence that the quality of the HS controls microbial growth. In total, net‐heterotrophy may result from HS‐mediated suppression of primary production by the quinone structures and/or from HS‐mediated support of microbial growth. As there is also evidence that HS have the potential to support photoautotrophic growth and suppress microbial growth, the opposite community effect could result. Consequently, dissolved organic carbon (DOC) has to be chemically characterised, rather than simply measuring bulk DOC concentration. 6. In sum, dissolved HS interact with freshwater organisms in a variety of ways in unenriched humic lakes. In addition to the well known effects of HS on light regime, for example, and the direct and indirect supply with carbon (energy), other interactions may be much more subtle. For instance, HS may induce internal biochemical stress defence systems and have the potential to cause acclimatisation and even adaptation. We are just at the beginning of understanding these interactions between dissolved HS and freshwater organisms.     

Personality and body condition have additive effects on motivation to feed in Zebra Finches Taeniopygia guttata

Several hypotheses have been proposed to account for the adaptive evolution of personality, defined as inter‐individual differences in behaviour that are consistent over time and across situations. For instance, the ‘pace‐of‐life syndrome’ hypothesis suggests that personality evolved as a behavioural correlate of life‐history trajectories that vary within populations. Thus, proactivity, corresponding to higher exploratory tendencies or higher boldness levels, has been linked to higher productivity or mortality rates. However, the extent to which proactivity is associated with a higher motivation to forage remains poorly understood. Moreover, although personality and its effects on foraging behaviour are usually considered to be independent of any motivational or nutritional state, few studies so far have challenged this. Here we show that personality traits, both individually or combined using a principal component analysis, and body condition have additive effects on latency to feed following food deprivation in the Zebra Finch Taeniopygia guttata, with personality accounting for 41% and body condition for about 20% of the total variation in latency to feed. In accordance with the pace‐of‐life syndrome hypothesis, latency to feed was negatively related to the degree of proactivity and positively related to body condition. Thus, proactive individuals and individuals in poorer condition were quicker to start feeding after a period of food deprivation. The absence of a significant interaction between personality and body condition further suggests that the effect of personality was independent of body condition. We discuss the relevance of our results in relation to the different factors influencing foraging in birds. Moreover, we place our results within a life‐history framework by emphasizing the correlated evolution of life‐history traits and personality.     

Land snail diversity in the monsoon tropics of Northern Australia: revision of the genus Exiligada Iredale, 1939 (Mollusca: Pulmonata: Camaenidae), with description of 13 new species

Vast parts of the monsoon tropics of Australia feature semi‐arid habitats, which are generally thought to harbour a depauperate land snail fauna as compared to the mesic continental fringes, in particular the Australian wet tropics. However, our knowledge of land snails inhabiting these often remote environments is still very patchy. In order to improve the understanding of land snail diversity in the monsoon tropics, we revised the camaenid land snail genus Exiligada based on comprehensive collections, undertaken by use of helicopters on remote limestone outcrops in the Northern Territory and in Western Australia. Based on comparative analyses of shell and genital morphology and patterns of molecular differentiation, we recognize 15 species within Exiligada, 13 of which are newly described. In addition, we suggest a revised delimitation of the type species Exiligada negriensis, as compared to the latest available revision, by removing Exiligada qualis from its synonymy and recognizing it as a distinct species. A key for species identification is also provided. Molecular phylogenetic analyses strongly supported the monophyly of Exiligada with respect to other confamilial genera known to occur in the same geographical region. Most Exiligada species are narrowly endemic to restricted limestone outcrops that cover areas with a diameter of about 20 to 150 km. Within the distributional range of Exiligada, the ranges of up to seven species overlap but we never found more than three species to occur in sympatry at a given sampling site. We propose that species originated by allopatric differentiation, followed by secondary range expansion, leading to sympatric distributions. Our study confirms that less complex rock habitats in more xeric environments support no more than three sympatric species, this being likely to be a result of ecological exclusion. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 689–722.