Interdecadal changes in at‐sea distribution and abundance of subantarctic seabirds along a latitudinal gradient in the Southern Indian Ocean

Long‐term demographic studies have recently shown that global climate change together with increasing direct impacts of human activities, such as fisheries, are affecting the population dynamics of marine top predators. However, the effects of these factors on species distribution and abundance at sea are still poorly understood, particularly in marine ecosystems of the southern hemisphere. Using a unique long‐term data set of at‐sea observations, we tested for interdecadal (1980s vs. 2000s) changes in summer abundance and distribution of 12 species of Albatrosses and Petrels along a 30° latitudinal gradient between tropical and Antarctic waters of the southern Indian Ocean. There were contrasting effects of climate change on subantarctic seabird distribution and abundance at sea. While subtropical waters showed the highest rate of warming, the species that visited this water mass showed the greatest changes in distribution and abundance. The abundance of Wandering Albatrosses (Diomedea exulans), White‐chinned Petrels (Procellaria aequinoctialis) and Giant Petrels (Macronectes sp.) declined markedly, whereas the other species showed contrasting trends or did not change. With the exception of the White‐chinned Petrel, these decreases were at least partly related to regional increase in sea surface temperature. The southward shift of Wandering Albatross and Prions (Pachyptila spp.) distributions could be ascribed to species redistribution or decrease in abundance due to warming of the subtropical waters. Surprisingly, White‐chinned Petrel distribution shifted northward, suggesting more complex mechanisms. This study is the first to document a shift in species range in the Southern Ocean related to climate change and contrasting abundance changes. It suggests that some species might experience more severe impacts from climate change depending on the water masses they visit. As climate changes are predicted to continue in the next decades, understanding species responses to climate change is crucial for conservation management, especially when their conservation status is critical or unknown.     

Current distribution and potential extent of the most invasive alien plant species on La Réunion (Indian Ocean,Mascarene islands)

Abstract La Réunion Island has the largest area of intact vegetation of the islands in the Mascarene archipelago. Biological invasions are the primary threat to biodiversity in the intact habitats of the island (those not already transformed by agriculture and urbanization). Our study aimed to identify areas to prioritize in managing invasive alien plants for biodiversity conservation. We used extensive surveys of 238 distinct untransformed areas on La Réunion to define the current distribution patterns of all invasive species. Using expert knowledge, we compiled maps of the current distribution of the 46 most widespread/important invasive plants at the habitat scale (identified according to vegetation structure). Data from 440 botanical relevés for the 20 most threatening invasive alien plant species across the island and climatic envelope models were used to derive climatic suitability surfaces; these were used to map potential distributions for these species. More than 10 species invade 16.7% of the remaining habitat. Five habitat types are invaded by 25 or more species, and eight have fewer than 10 invasive alien plant species. Cluster analysis based on presence/absence of species in the 18 habitat types produced eight groups of species that invade particular habitats. Potential distribution models show that some species have invaded large parts of their potential range (e.g. Fuchsia magellanica, Furcraea foetida, Hiptage benghalensis), whereas others have the potential to increase their range substantially (e.g. Clidemia hirta, Strobilanthes hamiltonianus, Ulex europaeus). Management implications are identified for both groups. Three broad groups of habitats were identified: (i) intact habitats with a low level of invasion (e.g. subalpine shrubland); (ii) moderately invaded habitats with varying levels of intactness (ranging from windward submountain rainforest to the Acacia heterophylla forest); and (iii) habitats with little remaining intact area and high levels of invasion (e.g. lowland rainforest). Different management interventions are appropriate for these three groups.     

Characterization of polymorphic microsatellite loci within a young Boophilus microplus metapopulation

Nine microsatellite loci from the cattle tick Boophilus microplus were isolated and characterized within New Caledonia. This Pacific island was invaded by the cattle tick from a few immigration events dating from mid‐20th century. A population survey involving 94 adult ticks indicated monomorphism at one locus, presence of null alleles at another, and high genetic diversity (0.61–0.72) at seven loci apparently suitable for population genetics studies. This opens the opportunity to dissect the populational mechanisms involved in the spectacular capacity of B. microplus to cope with local environmental heterogeneity during its recurrent invasions of tropical areas.     

Reproductive allocation in multinest colonies of the ponerine ant Pachycondyla goeldii

Abstract.  1.  Pachycondyla goeldii constitutes the only recorded case of a monogynous (i.e. one queen per colony) polydomous (i.e. several nests per colony) species in the Ponerinae subfamily. This study examines the impact of polydomy on reproductive allocation between nests (also called 'calies' in polydomous society) in Pachycondyla goeldii Forel, by: (i) recording the number of workers and sexuals in 67 nests belonging to 21 colonies; (ii) dissection of workers in nine nests containing a queen (QR nests), nine nests without a queen but associated to a QR nest (QL nests) and five nests belonging to colonies that permanently lost the queen (OR nests); and (iii) measuring the length of all eggs present in the nests (our laboratory study shows that queen-laid eggs were significantly longer than worker-laid eggs).
2. The number of workers was significantly higher in QR nests than in QL nests, while the number of virgin queens was significantly higher in QL nests compared with QR nests.
3. Worker ovarian activity is inversely related to queen proximity: highest in OR nests, intermediate in QL nests, and lowest in QR nests.
4. Egg length was highest in QR nests, where the queen was most likely the primary egg-layer, intermediate in QL nests, where eggs could have originated from both the queen and workers, and lowest in OR nests, where workers were the sole egg-layers.
5. We postulate that the proximal mechanism explaining differences between QR and QL nests is the pheromonal absence of the queen from QL nests and that the evolutionary reasons of these divergences between nest types are likely to originate from the different conflicts occurring in ant colonies.     

Ecological character displacement in competing common green lacewings in Europe: a route to speciation?

Competitive interactions among the three common green lacewing species of the Chrysoperla complex in Europe are presented. Four morphological characters were registered as semi‐quantitative traits to assess variation between populations. Data were obtained from 325 adults originating from 14 locations. A statistical approach was performed in conjunction with observations of ecological traits and a survey of genetic relationships assessed by mitochondrial DNA cytochrome b analysis. The results indicate character displacement in Chrysoperla affinis when living in sympatry with Chrysoperla carnea. The morphological traits of Ch. affinis sympatric with Ch. carnea differ from those of allopatric Ch. affinis, although the genetic distance between those strains was weak. This was associated with a large difference in microhabitats and premating behaviour. Variation in courtship songs manifests a process of speciation within related populations. Thus, that ecological switching can also promote character displacement is supported. This suggests that character displacement acts through phenotypic variability and mediates negative interactions among species. These findings suggest that the highest rate of speciation occurs in groups of species in which competition is the strongest. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 292–300.     

Rapid radiation of the Mediterranean Luciobarbus species (Cyprinidae) after the Messinian salinity crisis of the Mediterranean Sea, inferred from mitochondrial phylogenetic analysis

Phylogenetic relationships of 64 freshwater Barbus s.s. species distributed in basins around the Mediterranean Sea were assessed using cytochrome b sequences. Our results are in concordance with previous morphological and genetic studies, which proposed that these species belong to two major lineages (or subgenera): Barbus and Luciobarbus . We were particularly interested in phylogenetic relationships among species of the Luciobarbus lineage that are primarily found in the southern Mediterranean region from the Iberian Peninsula to the Middle East. In the Luciobarbus lineage, species that were previously attributed to the Capoeta genus were clustered. In this study, we observed short internodes between monophyletic groups having a geographical agreement around the Mediterranean. However, groups from the opposite sides of the Mediterranean Sea (Iberian Peninsula– Capoeta , north-western Africa–Middle East) seem to be phylogenetically close. We therefore infer that rapid radiation of Luciobarbus species in the Late Miocene better fits our data rather than gradual founder events in the southern Mediterranean. We propose that the biogeographical event along an east–west route, responsible for the present distribution of Luciobarbus species, was the 'Lago Mare' phase of the Mediterranean Sea that provided a rapid dispersal route over extensive distances. This provides new insights into the speciation pattern of this group, and may be of general use in the study of freshwater species in these regions.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 207–222.     

A multidisciplinary approach to discriminating different taxa in the species complex Pachycondyla villosa (Formicidae)

A multidisciplinary approach provides new evidence that strongly supports the differentiation of three taxa previously confounded in a single species, Pachycondyla villosa . All specimens studied were collected in the same location at Ilhéus, Bahia, Brazil. Bivariate plots of petiole heights vs. petiole lengths and isozyme patterns clearly differentiate the three taxa. Chain lengths and chemical structures of cuticular hydrocarbons are characteristic of each taxon. This congruent evidence shows that there are three different valid species. Ecological hypotheses are discussed to explain the benefits of these species remaining sympatric. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 75 , 249–259.     

Age-specific effect of heterozygosity on survival in alpine marmots, Marmota marmota

The fitness consequences of heterozygosity and the mechanisms underpinning them are still highly controversial. Using capture–mark–recapture models, we investigated the effects of individual heterozygosity, measured at 16 microsatellite markers, on age-dependent survival and access to dominance in a socially monogamous mammalian species, the alpine marmot. We found a positive correlation between standardized multilocus heterozygosity and juvenile survival. However, there was no correlation between standardized multilocus heterozygosity and either survival of older individuals or access to dominance. The disappearance of a significant heterozygosity fitness correlation when individuals older than juveniles are considered is consistent with the prediction that differences in survival among individuals are maximal early in life. The lack of a correlation between heterozygosity and access to dominance may be a consequence of few homozygous individuals attaining the age at which they might reach dominance. Two hypotheses have been proposed to explain heterozygosity-fitness correlations: genome-wide effects reflected by all markers or local effects of specific markers linked to genes that determine fitness. In accordance with genome-wide effects of heterozygosity, we found significant correlations between heterozygosities calculated across single locus or across two sets of eight loci. Thus, the genome-wide heterozygosity effect seems to explain the observed heterozygosity-fitness correlation in the alpine marmot.     

Distribution and Abundance of Endangered Florida Key Deer on Outer Islands

ABSTRACT Status assessment of endangered Florida Key deer (Odocoileus virginianus clavium) is currently limited by a paucity of information regarding population estimates for outer islands, which collectively comprise approximately 70% of potential habitat within the Key deer range. Practical limitations and financial considerations render traditional survey techniques impractical for application on remote outer islands. Our objective was to evaluate the utility of infrared-triggered cameras to estimate Key deer abundance on outer islands. We used digital infrared-triggered cameras and mark-resight methods to estimate Key deer abundance on 20 outer islands. Abundance estimates for primary subpopulations ranged from 15 to 16 for Howe Key, 5 to 10 for Knockemdown complex, and 13 to 17 for Little Pine Key. Other island complexes such as Ramrod Key, Water Key, and Annette complex maintain only small subpopulations (i.e., ≤5 individuals) and other previously inhabited island complexes (e.g., Johnson complex and Summerland Key) no longer maintain subpopulations. Key deer abundance was well below estimated carrying capacities on all outer islands, with larger natural populations occurring closest to Big Pine Key. Our results suggest that camera-based surveys offer a practical method to monitor abundance and population trends of Key deer on outer islands. Our study is the first to estimate Key deer abundance in these areas using technically structured model-based methods and provides managers with current and baseline information regarding Key deer subpopulations.