Habitat Openness Research Articles

Incorporating environmental considerations in managing Egyptian geese on golf courses in South Africa

ABSTRACTEgyptian geese (Alopochen aegyptiaca) occur in large numbers on golf courses in southwestern South Africa. They cause physical and financial damage to the courses and are a nuisance to golfers and golf course managers. Most control measures used to reduce the problem have been unsuccessful. We investigated the potential for environmental management options by determining which landscape features attract geese to certain areas within golf courses and cause them to avoid others. Goose vigilance levels were lower in use than in non‐use areas regardless of group size (t1 = 5.837, P ≤ 0.001, F1 = 53.877, P ≤ 0.001). This behavior suggested that geese were attracted to some areas because they perceive them to be safer. Landscape features that attracted Egyptian geese were large open patches of lawn (>1.5 ha) and proximity to water bodies (<100 m). Water bodies should not be adjacent to open foraging or loafing areas. Other modifications may include planting herbaceous vertical vegetation around water bodies and open fairways to reduce habitat openness and predator visibility. Our results suggest that the level of the goose problem at any golf course is a consequence of the intrinsic properties of that course and not influenced by the extent of the problem at nearby golf courses. © 2014 The Wildlife Society.

Land surface skin temperature captures thermal environments of C3 and C4 grasses

AbstractAimNumerous studies have documented ecological sorting of C3 and C4 grasses along air temperature gradients. However, phylogenetically structured analyses suggest that closely related C3 and C4 grasses (in the same PACMAD clade: Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae and Danthonioideae) occur in environments with similar air temperature, challenging our understanding of how the photosynthetic pathway influences grass biogeography. To better understand thermal differences between C3 and C4 grass lineages, we analysed the surface radiative temperature as an alternative measure that is more closely aligned with plant microclimate.LocationHawaiian Islands, USA.MethodsWe used the MODIS land surface temperature (LST) product, a satellite‐based measurement of radiative temperature. We compared LST with mean annual air temperature (MAT) for locations where C3 and C4 grass species were collected. We also utilized other satellite products, like MODIS tree cover, as a proxy for relative habitat openness where these grasses occur.ResultsComparisons of C3 lineages [in BEP (Bambusoideae, Ehrhartoideae and Pooideae) and PACMAD clades] and C4 lineages (PACMAD clade only) illustrate the differing thermal environments for each group. C4 taxa are found in the environments with the highest MAT, followed by C3 PACMAD species. By contrast, C3 PACMAD species are found in the environments with the coolest LST, and the LST values for C3 BEP species are substantially higher than their MAT values. The difference in LST between C3 and C4 PACMADs is larger than the difference in MAT between these groups.Main conclusionsThough LST has been used infrequently in ecology and biogeography, it is intimately related to water and energy balance and ecosystem structure, and should more accurately capture plant temperatures and microclimates than MAT. Our results provide support for a pronounced thermal difference in the environments of closely related C3 and C4 grass taxa, and show that C3 PACMADs occur in the coolest and least variable thermal environments, probably due to the greater tree cover of these habitats.

The effects of edge-interior and understorey-canopy gradients on the distribution of saproxylic beetles in a temperate lowland forest

Spatial distribution of arthropods in woodlands has crucial implications for biodiversity conservation and forest management. However, its determinants are insufficiently known. In particular, studies on arthropod vertical distribution in temperate woodlands report contrasting patterns that are difficult to explain in the current theoretical framework. Using flight intercept traps, we investigated vertical and horizontal distribution and diversity of saproxylic beetles in the understorey and the upper canopy at the edge and in the interior of a temperate, closed-canopy, deciduous forest in South-Eastern Czech Republic. At the forest edge, number of species was >60% higher than in the interior. Preference for forest edge were better pronounced in the understorey than in the canopy. Although number of species did not differed between the forest strata, vertical distribution of individual species as well as the whole assemblages differed between edge and interior. In the forest interior, most (∼80%) species exhibited higher preference for the canopy than at its edge. Multivariate analysis indicated that beetle distribution was affected by variables related to habitat openness and light availability. The results suggest that: (i) Vertical stratification of arthropod assemblages and individual species is context-dependent and variable even within a single forest patch. (ii) Vertical and horizontal distribution of arthropods is driven mainly by sunlight availability and habitat openness. (iii) In the closed canopy forest, the horizontal edge-interior gradient affects distribution of saproxylic beetles more than the vertical understorey-canopy gradient.

Applying distribution model projections for an uncertain future: the case of the Pacific oyster in UK waters

ABSTRACT The inherent complexity of the environment is such that attempts to model it must operate under simplifications and assumptions. Considering predictions from alternative models, with a range of assumptions and data requirements, therefore provides a more robust approach. The intractability and uncertainty resulting from a suite of predictions may hinder the application of science in policy, where a single prediction with little ambiguity or uncertainty would be most desirable. Few studies modelling species' distributions attempt to present multi‐model outputs in a format most useful to the non‐modelling community, and none of these have done so for the marine environment. The problem of uncertainty is particularly prevalent in predicting the distribution of invasive alien species under climate change. As invasive alien species are one of the main drivers of biodiversity loss and may incur significant economic costs, the benefit of applying predictions to highlight areas of possible establishment and inform policy and management may be large. An ensemble prediction is used to assess the distribution of suitable habitat for the Pacific oyster, Crassostrea gigas, in UK waters both currently and in the future. The ensemble incorporates predictions from three species distribution models, using data from two global climate models. A method is developed highlighting the agreement of the ensemble, further applying threshold values to retain information from constituent predictions in the final map of agreement. Ensemble predictions made here suggest that Pacific oyster will experience an opening of suitable habitat in northern UK waters, reaching the Faroe Islands and the eastern Norwegian Sea by 2050. Habitat suitability will increase with warming temperatures in the English Channel and Central North Sea for this species. The approaches applied here can be incorporated into risk assessment frameworks for invasive species, as stipulated in the Convention on Biological Diversity. Copyright © 2013 John Wiley & Sons, Ltd.

Factors shaping the evolution of colour patterns in Australian agamid lizards (Agamidae): a comparative study

Identifying general patterns of adaptive coloration in animals can help to elucidate the evolutionary processes that generate them. We examined the evolution of colour patterns in Australian agamid lizards, a morphologically and ecologically diverse group that relies primarily on visual communication. We tested whether certain types of colour (yellow–reds and black) were likely to be used as sexual signals, as indicated by their association with indices of sexual selection, namely, sexual dichromatism and sexual dimorphism in body size and head shape. We then tested whether sexually dichromatic colours are associated with specific patterns (uniform, mottled, striped, blotched, reticulated) or ecological variables such as habitat openness, arboreality, and substrate type. The presence of yellow–red on lateral and ventral body regions and black on ventral body regions was significantly more common in males than females. Lateral yellow–red in males was associated with the total extent of sexual dichromatism and size dimorphism, whereas ventral yellow–red was associated with sexual dichromatism. Both lateral and ventral yellow–red were associated with uniform patterning, suggesting that sexual signals in male agamid lizards may often comprise uniform patches or flushes of yellow–red. Although ventral black coloration was more prevalent on males (i.e. strongly sexually dichromatic), it was not associated with indices of sexual selection, suggesting that, in agamid lizards, yellow–red coloration is more likely to be sexually selected than black. Sexually dichromatic coloration was not strongly associated with any of the ecological variables measured. We found some associations, however, between female dorsal patterns and ecological variables, suggesting that female patterns are influenced by natural selection. Biological Journal of the Linnean Society, 2013, 109, 101–112.

Contrasting the distribution of phenotypic and molecular variation in the freshwater snail Biomphalaria pfeifferi, the intermediate host of Schistosoma mansoni.

Population differentiation was investigated by confronting phenotypic and molecular variation in the highly selfing freshwater snail Biomphalaria pfeifferi, the intermediate host of Schistosoma mansoni. We sampled seven natural populations separated by a few kilometers, and characterized by different habitat regimes (permanent/temporary) and openness (open/closed). A genetic analysis based on five microsatellite markers confirms that B. pfeifferi is a selfer (s≈0.9) and exhibits limited variation within populations. Most pairwise FST were significant indicating marked population structure, though no isolation by distance was detected. Families from the seven populations were monitored under laboratory conditions over two generations (G1 and G2), allowing to record several life-history traits, including growth, fecundity and survival, over 25 weeks. Marked differences were detected among populations for traits expressed early in the life cycle (up to sexual maturity). Age and size at first reproduction had high heritability values, but such a trend was not found for early reproductive traits. In most populations, G1 snails matured later and at a larger size than G2 individuals. Individuals from permanent habitats matured at a smaller size and were more fecund than those from temporary habitats. The mean phenotypic differentiation over all populations (QST) was lower than the mean genetic differentiation (FST), suggesting stabilizing selection. However, no difference was detected between QST and FST for both habitat regime and habitat openness.

Habitat management for Red–backed Shrike, Lanius collurio, conservation in farmland systems

The Province of Verbano Cusio Ossola, North-Eastern Piedmont, carried out a LIFE-Nature project during the period 2003-2007. The project focused on a Natura 2000 site, located along the middle course of river Toce. One of the interventions was directed at the conservation of the breeding population of Lanius collurio through dedicated management of lowland hay meadows (with maintenance of unmown portions) and shrublands (with increasing habitat openness in overgrown shrublands). Those interventions resulted an increase in the local breeding population of the species from 9 to 25 pairs in 5 years.

Traits explain community disassembly and trophic contraction following experimental environmental change

AbstractMany ecosystems are currently undergoing dramatic changes in biodiversity due to habitat loss and climate change. Responses to global change at the community level are poorly understood, as are the impacts of community disassembly on ecosystem‐level processes. Uncertainties remain regarding the patterns of extirpation and persistence under single vs. multiple forms of environmental change. Here, we use a trait‐based and food web approach to examine the effects of experimentally changing moisture, temperature and habitat ‘openness’ on a functionally important group of microarthropods associated with a boreal forest floor bryosphere (detrital moss) system. Overall, the outcome of community disassembly was mediated by the correlation between our environmental factors and species traits, particularly body size. Minor increases in summer temperatures maintained greater species richness, whereas drought stress had a significant negative effect on community‐level abundance and richness. These effects were reflected in modifications to the community‐wide body‐size spectra. Habitat openness alleviated biodiversity loss in the larger‐bodied species of the most abundant taxonomic group, but did not fully mitigate the effects of drought. The most striking result of this experiment was an overall contraction of the food web among persistent species under drought stress (i.e. those not extirpated by environmental change). These results suggest that major changes in boreal microarthropod community structure are likely to occur in response to common forms of global change. Moreover, the contraction in trophic structure even amongst tolerant species suggests that ecosystem function within the bryosphere can be altered by environmental change.

Variation in habitat use of coexisting rodent species in a tropical dry deciduous forest

Use of habitat is a critical component related to structure of small-mammal communities, with partitioning occurring primarily along dimensions of microhabitat, although use of microhabitat often does not explain fully use at a macrohabitat level. Through grid studies of small mammals in coastal Colima, Mexico (during January 2003–2005), we appraised influence of available habitat, species richness, abundance, and cumulative abundance of other small mammals on variation in habitat used by species. We evaluated 14 habitat variables (reflecting ground cover, slope, canopy, and vegetation density on vertical and horizontal axes) and developed a composite variable (principal component 1) reflecting general openness of habitat through which we addressed habitat use. For the four most common mammalian species (Sigmodon mascotensis, Heteromys pictus, Baiomys musculus, and Oryzomys couesi), two measures of variation in habitat used were employed to estimate niche breadth, one of which assessed variation in habitat use relative to variation present on a grid. Sigmodon mascotensis and B. musculus preferred areas that were more open, and H. pictus and O. couesi occupied less-open areas; breadth of habitat use did not differ interspecifically. Habitat use was more variable on grids with more variability in habitat, although not greater than chance expectations. Findings do not lend support to the resource-breadth hypothesis as an explanation for population densities of species at a local level or the habitat-heterogeneity hypothesis as a predictor of species richness. Variation in habitat used by S. mascotensis did not proportionally increase when diverse habitat was available but was greater when the species was more abundant. For H. pictus, when cumulative abundance of other small mammals was greater, breadth of habitat used was greater. Intraspecific density-dependent habitat selection may result in S. mascotensis selecting a greater variety of habitats, while greater interspecific abundance is related to a greater range in use of habitats by H. pictus. Baiomys musculus used a higher proportion of habitat relative to that available when more species were present on a grid. Variation in habitat used by O. couesi was unrelated to any factor examined. Overall, the four species responded in notably different ways with respect to availability of habitat, abundance, and presence of other species.

Partial migration in roe deer: migratory and resident tactics are end points of a behavioural gradient determined by ecological factors

Ungulate populations exhibiting partial migration present a unique opportunity to explore the causes of the general phenomenon of migration. The European roe deerCapreolus capreolusis particularly suited for such studies due to a wide distribution range and a high level of ecological plasticity. In this study we undertook a comparative analysis of roe deer GPS location data from a representative set of European ecosystems available within the EURODEER collaborative project. We aimed at evaluating the ecological factors affecting migration tactic (i.e. occurrence) and pattern (i.e. timing, residence time, number of migratory trips). Migration occurrence varied between and within populations and depended on winter severity and topographic variability. Spring migrations were highly synchronous, while the timing of autumn migrations varied widely between regions, individuals and sexes. Overall, roe deer were faithful to their summer ranges, especially males. In the absence of extreme and predictable winter conditions, roe deer seemed to migrate opportunistically, in response to a tradeoff between the costs of residence in spatially separated ranges and the costs of migratory movements. Animals performed numerous trips between winter and summer ranges which depended on factors influencing the costs of movement such as between‐range distance, slope and habitat openness. Our results support the idea that migration encompasses a behavioural continuum, with one‐trip migration and residence as its end points, while commuting and multi‐trip migration with short residence times in seasonal ranges are intermediate tactics. We believe that a full understanding of the variation in tactics of temporal separation in habitat use will provide important insights on migration and the factors that influence its prevalence.

Evolutionary losses of facial stripes in New World pitvipers

Associations between the evolutionary loss or gain of colours and habitat can be informative about how environment drives colour evolution, and provide insight into their functions. Despite a wealth of studies on colours, the function of many colour patches are not well understood. This is especially the case for dark facial markings. Dark facial stripes are common in snakes, including many pitvipers, which possess facial stripes that extend from the eye towards the corner of the mouth. We investigated whether the evolutionary loss or gain of facial stripes in New World pitvipers is associated with activity period and habitat, hoping to shed light on their function. First, we examined whether evolutionary loss or gain of facial stripes is associated with nocturnal or diurnal activity. It has been suggested that facial stripes may protect the venom from ultraviolet radiation, which would be higher in diurnal species. Similarly, snakes in open habitats may experience higher ultraviolet radiation than those in closed habitats. Alternatively, we examined whether evolutionary loss or gain of facial stripes is associated with terrestrial or non-terrestrial habitat use. Studies on similar facial markings in other vertebrates indicated that they have a signalling function. If facial stripes in pitvipers have a signalling function, arboreal or saxicolous habitat use may limit signal effectiveness. Hence, we hypothesized that there may be an association between facial stripe evolution and habitat use. Using combined phylogenies that included almost every New World pitviper species, we tested correlations between facial stripes and ultraviolet exposure (activity period and habitat openness) and habitat use (terrestrial or non-terrestrial) using concentrated-changes tests and Pagel’s correlation tests. Our data did not support the hypothesis that ultraviolet exposure influenced facial stripe evolution. Instead, the evolutionary loss of facial stripes was associated with non-terrestrial habitat use, such as arboreal and saxicolous habitats. In these habitats, we suggest the effectiveness of facial stripes as a signal would be limited, leading to their evolutionary loss. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 923–933. ADDITIONAL KEYWORDS: aposematic warning – rattlesnakes – signals – ultraviolet radiation.

Spatial and temporal factors influencing sightability of elk

AbstractFew tracking studies consider seasonal changes in ability to re‐sight wildlife, despite potential for biases in sightability to mislead our interpretation of models of movement and abundance. We developed seasonal sightability models based on visual observations of radio‐collared elk (Cervus elaphus) in Manitoba, Canada, through 6 seasons. We located 377 elk 8,862 times using aerial telemetry from 2002 to 2009. We tested the hypothesis that sites where we were able to visually observe radio‐collared elk during aerial telemetry differed from sites where collared elk were known to be present but could not be sighted. Relationships varied with season and elk sightability was influenced by forest type, habitat openness, distance to edge, and time of day. Our results confirm that observers have the highest probability of detecting elk in early and late winter. However, factors such as day length, which increases by 64% during this period, suggest that fewer impediments to detection exist in late winter. Our findings reinforce the need to account for seasonal as well as spatial changes in habitat‐specific sightability models. © 2011 The Wildlife Society.

Predicting spatial occurrence of beetles and pseudoscorpions in hollow oaks in southeastern Sweden

We modelled presence/absence per tree of beetles and pseudoscorpions living in tree hollows in relation to trunk circumference, habitat openness, and connectivity (= density of hollow oaks in the surrounding area), using data from 281 oaks. The presence/absence models were then used to predict species’ occurrences in a county (11,600 km2) in southeastern Sweden. For eight of the nine species, the most parsimonious occupancy model included a positive relationship with connectivity and at least one tree characteristic. Occupancy underestimates from occurrence records—the ratio of the area of occupancy based on our predictive model to the area of occupancy based on occurrence records—varied between 3 and 83 among species when using occurrence records up to 1993, with significantly larger underestimates for smaller beetle species. Today (after extensive surveys), underestimation has decreased to 1.3–25, confirming that calculations solely based on species occurrence records greatly underestimate the area of occupancy. We suggest this should be taken into account to a greater extent and in a clearer way than today when constructing red lists. The radius of the connectivity measure that generated the best fit varied between 135 and 2,857 m among species, with longer distances for more threatened species. Consequently, preservation of the most threatened species (Elater ferrugineus and Tenebrio opacus) requires conservation efforts at larger spatial scales than required to protect Osmoderma eremita, which frequently has been used as an indicator and umbrella species.

C4 eudicots are not younger than C4 monocots

C(4) photosynthesis is a plant adaptation to high levels of photorespiration. Physiological models predict that atmospheric CO(2) concentration selected for C(4) grasses only after it dropped below a critical threshold during the Oligocene (∼30 Ma), a hypothesis supported by phylogenetic and molecular dating analyses. However the same models predict that CO(2) should have reached much lower levels before selecting for C(4) eudicots, making C(4) eudicots younger than C(4) grasses. In this study, different phylogenetic datasets were combined in order to conduct the first comparative analysis of the age of C(4) origins in eudicots. Our results suggested that all lineages of C(4) eudicots arose during the last 30 million years, with the earliest before 22 Ma in Chenopodiaceae and Aizoaceae, and the latest probably after 2 Ma in Flaveria. C(4) eudicots are thus not globally younger than C(4) monocots. All lineages of C(4) plants evolved in a similar low CO(2) atmosphere that predominated during the last 30 million years. Independent C(4) origins were probably driven by different combinations of specific factors, including local ecological characteristics such as habitat openness, aridity, and salinity, as well as the speciation and dispersal history of each clade. Neither the lower number of C(4) species nor the frequency of C(3)-C(4) intermediates in eudicots can be attributed to a more recent origin, but probably result from variation in diversification and evolutionary rates among the different groups that evolved the C(4) pathway.

Resources driving landscape-scale distribution patterns of grazers in an African savanna

In order to effectively manage and conserve indigenous herbivores, a good understanding is needed of how resources drive their distribution patterns. This study employed a unique dataset to test a range of ecological theories and hypotheses on free-ranging grazers. Using aerial census data collected over 14 yr across the 2 million ha Kruger National Park (South Africa), this study employs spatial autologistic regression models to explore the spatial relationships that exist between the distribution of eight indigenous grazer species and a set of resource variables. It was found that ecological theories relating to feeding guild, water-dependence, allometric scaling, gut-morphology and vulnerability to predation could explain most of the grazer distribution patterns observed in relation to surface-water, forage quality, forage quantity and habitat openness. All the grazers studied were water-dependent and occurred close to a permanent source of water in the dry season. This was ascribed to the lack of moisture in the diet of grazers during the dry season. Most ruminants' distribution patterns were significantly associated with areas of high forage quality whereas hind-gut fermentors were neutral towards forage quality. Average forage quantity was not a significant predictor of long-term, landscape-scale distribution patterns for any of the grazer species studied. Most small- and medium-bodied grazers preferred open habitats above closed habitats, probably due to higher visibility and a lower predation risk. Large-bodied grazers did not bias their distribution patterns towards open habitats. The way in which grazers distribute themselves with respect to different resources can potentially inform management actions on appropriate scales.

Wetland Use and Selection by Breeding Waterbirds in the Boreal Forest of Quebec, Canada

Wetlands of remote forested landscapes of Quebec support numerous species of breeding waterbirds yet species-habitat associations remain poorly quantified. From 1990 to 2005, we conducted systematic helicopter surveys of breeding waterfowl and common loons (Gavia immer) across a 540,000-km2 forested region of Quebec. Data from this survey were used to investigate local habitat use and selection by waterbirds, based on a wetland classification system derived from digital forestry maps. Detailed indicated-breeding-pair (IBP) distributions were developed for broad aquatic, wetland, and shoreline habitat types. We also estimated selection ratios within groups of similar habitat types. Small (≤8 ha), connected ponds were highly used and selected by five dabbling duck species and by wood duck (Aix sponsa), Canada goose (Branta canadensis), ring-necked duck (Aythya collaris), hooded merganser (Lophodytes cucullatus), common goldeneye (Bucephala clangula), and Barrow’s goldeneye (B. islandica). Dabbling duck species, wood duck, and Canada goose made extensive use of streams (25–41% of all IBP). Community organization was mainly driven by openness of aquatic habitat and water movement, i.e., from lentic to lotic habitats. Failure to include streams in waterfowl surveys and habitat mapping could produce biased estimates of wetland habitat use and selection in the boreal forest.

Nowhere to run: the role of habitat openness and refuge use in defining patterns of morphological and performance evolution in tropical lizards

For species from open habitats with little cover and few refugia, selection should favour morphologies that enhance performance at tasks that enable rapid movement across open areas. Similarly, selection should also favour traits that enable rapid access and movement within suitable refugia. This study examined the relationship between habitat openness, refuge use, morphology and performance of 19 species representing 23 populations of tropical Lygosomine skink. Species from this group occupy a wide array of habitats from open forest and open rocky intertidal zones to high-altitude heaths and dense, closed forests. Species that occupied open habitats were faster at sprinting, climbing and had better cling ability than species from more cluttered, closed habitats. In addition, species from habitats that used rock crevices as refuges had enhanced sprinting ability. This study shows the importance of both habitat openness and refuge type in the evolution of both the morphology and performance in lizards.

Processes driving male breeding colour and ecomorphological diversification in rainbow skinks: a phylogenetic comparative test

We used a phylogenetic comparative approach to investigate the importance of ecological shifts in the diversification of both signalling traits and ecomorphological traits in a diverse group of Australian skinks (Carlia). First, we tested whether divergence in male breeding coloration is associated with shifts in habitat openness. Second, we examined whether the type or location of male breeding coloration changes predictably with habitat openness. Third, we tested the ecomorphological predictions that body size should vary in relation to habitat openness and that limb length, toe length and head depth should vary with substrate use. Divergence in male breeding coloration was positively associated with shifts in habitat openness. Our results also indicate that species occupying more open habitats tend to use male sexual signals located on lateral body regions and not necessarily on body regions that are potentially more concealed from aerial predators (e.g. chest and throat). With regard to ecomorphological traits, habitat openness appears to have no predictable influence on body size at the inter-specific level, contrary to expectations based on intra-specific studies. However, consistent with functional predictions, we found that preference for rocky habitats is associated with relatively longer hind limb length, presumably due to selection for greater speed and jumping ability on these substrates. Overall, results of this study support the hypothesis that ecological shifts play a central role in promoting morphological diversification.

Cyclic climate and vegetation change in the late Miocene of Western Bulgaria

A late Miocene paludal to lacustrine sequence from a carbonate basin in NW Bulgaria (Staniantsi Basin) is analysed displaying up to 27 rhythmically bedded sedimentary cycles. In the lower part of the sequence, the cycles consist of alternating autochthonous brown coal and marls containing diverse mollusc assemblages. The upper part of the sequence is characterized by alternating dark to light grey clays and calcareous silts. A palynomorph record comprising 163 samples is analysed by statistical means to reconstruct vegetation changes. The Coexistence Approach is used to calculate quantitative palaeoclimate records for 6 parameters. The studied section displays hierarchical cyclicity patterns. Longer-term cycles possibly related to eccentricity (period ~ 100 kyr) are present in the palynomorph record and show climate changes of warmer/wetter and cooler/drier periods in combination with frequency oscillations of thermophilous elements. Short-term cycles most probably related to precession (period ~ 21.7 kyr) are expressed by alternations of brown coal and marl/shell beds and show cyclic change in peat-forming vegetation related to oscillations of the groundwater level. As a triggering mechanism, wetter/warmer and drier/cooler climate phases related to orbital precession are probable. In addition, sections sampled at high resolution display small scale climate and vegetational variability. As is shown by the analysis ferns were an important component of the peat-forming vegetation, while outside the mire, a wetland vegetation consisting of pioneers and a mixed mesophytic forest with evergreen shrubs existed. An oligo- to mesotrophic slightly alkaline lake became repeatedly established with a diverse mollusc fauna and a dense hydrophytic vegetation with characean meadows. In the upper part of the section, a spreading of herbaceous vegetation is observed, also known from other contemporaneaous palynomorph records in Bulgaria and surrounding areas. The increase of Asteraceae in the upper part of the section, combined with a marked decrease in woody taxa, points to an opening of habitats and a decrease in mean annual precipitation. This trend is paralleled by the mollusc fauna which yields several terrestrial, partly xerophilous taxa.

LIFE ON THE ROCKS: HABITAT USE DRIVES MORPHOLOGICAL AND PERFORMANCE EVOLUTION IN LIZARDS

As a group, lizards occupy a vast array of habitats worldwide, yet there remain relatively few cases where habitat use (ecology), morphology, and thus, performance, are clearly related. The best known examples include: increased limb length in response to increased arboreal perch diameter in anoles and increased limb length in response to increased habitat openness for some skinks. Rocky habitats impose strong natural selection on specific morphological characteristics, which differs from that imposed on terrestrial species, because moving about on inclined substrates of irregular sizes and shapes constrains locomotor performance in predictable ways. We quantified habitat use, morphology, and performance of 19 species of lizards (family Scincidae, subfamily Lygosominae) from 23 populations in tropical Australia. These species use habitats with considerable variation in rock availability. Comparative phylogenetic analyses revealed that occupation of rock-dominated habitats correlated with the evolution of increased limb length, compared to species from forest habitats that predominantly occupied leaf litter. Moreover, increased limb length directly affected performance, with species from rocky habitats having greater sprinting, climbing, and clinging ability than their relatives from less rocky habitats. Thus, we found that the degree of rock use is correlated with both morphological and performance evolution in this group of tropical lizards.