Life history and demographic features of Astragalus nitidiflorus, a critically endangered species

Astragalus nitidiflorus is an endangered perennial, but short-lived legume of SE Spain, which has been re-found after 100 years. To identify possible weak points that might contribute to its rarity and hamper its conservation, this paper presents data concerning location, habitat, demographic features and reproductive biology of the species. Censuses of three cohorts of seedlings show that the seedling stage is the most critical in the life cycle. The adult plants show a long flowering season with a high degree of synchrony. Despite the low reproductive success of the species, the annual seed production is very high due to the high floral production. The data show that A. nitidiflorus is a facultative xenogamous species, but the presence of pollinators can enhance fruit set. The viability of the species is not limited by the flowering and fruiting process, however the maintenance of the habitat in the early successional stages seems to be the critical point for long-term survival of the species.     

Ectoparasite and hemoparasite infection in a diverse temperate lizard assemblage at Macraes Flat, South Island, New Zealand

A lizard assemblage at Macraes Flat, New Zealand, comprising the common skinks Oligosoma maccanni and Oligosoma nigriplantare polychroma, the endangered species Oligosoma grande and Oligosoma otagense, and the common gecko Hoplodactylus maculatus, was studied to determine the prevalence of ectoparasites and hemoparasites. The mites Odontacarus lygosomae and Ophionyssus scincorum infected all Oligosoma spp. only, and the mite Neotrombicula naultini infected only H. maculatus. The hemoparasite Hepatozoon lygosomarum infected all Oligosoma skinks, except O. n. polychroma. Oligosoma otagense had the highest infection levels of all parasites by several orders of magnitude. For all lizard species, there was no difference in mite prevalence between adult males and adult females, but juveniles were less often infected. For all skink species, there was a significant relationship between presence of the hemoparasite He. lygosomarum and infection intensity of the supposed vector, O. scincorum. It is unclear if patterns of parasite infection reflect species-specific susceptibility, host-parasite species-specific spatial ecology, or environmentally induced host physiological impairment. Considering the threatened nature of O. otagense, evidence of high parasitemia should stimulate further investigation.     

Life history traits as predictors of plant rarity, with particular reference to hemiparasiticOrobanchaceae

We made a comparison between life history and reproductive characteristics of a group of Dutch rare (30) and common (105) plant species, all dicotyledonous and insect-visited forbs. The traits life span, clonality, breeding system, seed production, seed dispersal, and soil seed bank longevity are considered. All trait values have been ranked according to their possible effect on the vulnerability of a species for extinction, where low values indicate a low risk and high values a high risk for a species. Rare and common plants differed significantly in four traits: seed production, breeding system, seed bank longevity and clonality. The discriminant analysis showed that 79% of the 135 species was correctly classified in the group they presently belong to. Especially species that are rare now but were much more common 50–100 years ago were classified as being common species, pointing at the detrimental effect of habitat loss these species encountered at which they have not yet been able to adapted to. The data set include eight hemiparasitic plant species (familyOrobanchaceae), of which six are endangered in The Netherlands and two more common. Both rare and common hemiparasites scored high traits values, indicating that they are vulnerable for extinction. The hemiparasites had several characteristics in common: they are all annuals or biennials that have no means of clonal reproduction. They all have non-clustered, zygomorphic flowers that produce nectar and have a precise pollen presentation and are mainly visited by (bumble) bees. Mean life span was significantly shorter in the eight hemiparasiticOrobanchaceae than in the non-hemiparasiticScrophulariaceae used for comparison (4 species). Overall, we concluded that hemiparasitic plants have a special combination of life history traits which makes them vulnerable for local and regional extinction.     

Climate change,mean sea levels,wetland decline and the survival of the critically endangered Capricorn Yellow Chat

An isolated population of ~30 Capricorn Yellow Chats (Epthianura crocea macgregori) (Aves: Meliphagidae) occurs on a grassy marine plain (~4000 ha) with complex fresh to hypersaline wetlands bordering unvegetated salt flats and mangroves, the majority less than 2 m above mean sea level (MSL). While there are several species of sedge on the marine plain, only one, a tall salt‐tolerant sedge, Schoenoplectus subulatus, regularly provides tall cover and nesting habitat on the marine plain. Comparison of vegetation data between 2002 and 2018 at four breeding sites showed a loss of S. subulatus at two of the sites in conjunction with persistent extreme hypersalinity. In contrast, sites where S. subulatus recovered had elevated salinity levels coinciding with a drought in 2005–2008, but subsequently returning to pre‐drought levels. Concomitant with the loss of S. subulatus was a substantial decline in Capricorn Yellow Chat abundance. Possible drivers of persistent hypersalinity were an increase in sea level and consequent greater tidal ingress. The two most severely affected sites were relatively close to tidal influence and low points in the landscape. Evaluation of MSL data showed that habitat decline from 2002 to 2018 occurred over a period in which sea level rose by ~80 mm. While it is recognised that other variables are important, this study indicates that if sea‐level rise continues at the 2011–2017 rate of ~8.3 mm per annum, the Curtis Island marine plain will become unsuitable for Capricorn Yellow Chats in the next 60 years or less. Sixty years is likely to be a conservative estimate given that sea‐level rise rates are projected to increase further, as are the influence of more extreme weather events such as drought and storm surges on persistence of key vegetation. Ramifications for other Capricorn Yellow Chat sites and marine plain‐dependent fauna such as shorebirds also need consideration.     

Intraspecific variation in seedling drought tolerance and associated traits in a critically endangered,endemic Hawaiian shrub

ABSTRACT

Background

Climates are changing at a rate that exceeds the adaptive capacity of species, especially endangered species. Genetic variation and phenotypic plasticity are important for population persistence, yet few studies have linked traits to seedling performance under drought in endangered species.     

Life history traits of a European Messor harvester ant

We present life history traits of a Central European harvester ant, Messor cf. structor, determined by gyne and male dissections, behavioural assays, standardised brood photography and laboratory rearing of brood. Messor cf. structor is polygynous and builds up unicolonial populations. Sexuals develop from hibernated larvae in a univoltine cycle and become adult from late summer to late autumn. Neither intra- nor extranidal mating was observed in autumn, even though gynes and males were mature. In spring, after hibernation, intranidal mating without swarming flight took place, even though the flight muscles of alate sexuals were still fully developed. Received 3 March 2005; revised 4 May 2005; accepted 9 May 2005.     

Life history patterns in lizards of the arid and semiarid zone of Australia

Summary Studies on the life histories and population dynamics of lizards in the semiarid/arid zone of Australia are reviewed to identify the influence of size (female mean snout-vent length), phylogeny (family effects) and ecological parameters on the evolution of life history traits of these species. Species producing more than one clutch per year are larger than single-clutched ones. In an ANCOVA, significant effects of size and phylogeny on clutch size and on age at sexual maturity were found. Microhabitat (arboreal, terrestrial, and subterranean life style) also had an effect on clutch size, but only mediated through a significant interaction with size. However, results of the ANCOVAs depend on the families and ecological parameters included in the analyses. Therefore, caution is necessary in interpreting or generalizing the results; in any case, size and phylogeny explain only a small percentage of the observed variation. Nevertheless, a direct comparison of a set of syntopic/paratopic desert lizards supports and extends the main conclusions of the ANCOVA. A significant but small phylogenetic effect was found, and arboreal microhabitat was associated with greater age at sexual maturity. Activity (diurnal versus nocturnal) influenced yearly mortalities and clutch frequencies. For both, microhabitat and activity, predation levels and size-dependent mortality were the likely selective factors causing these correlations. The demographic environment explains the paucity of duurnal lizard species with fixed clutch sizes in the semiarid/arid zone of Australia. Possible causes for the evolution of fixed clutch sizes are discussed.     

Genetic diversity and population history of a critically endangered primate, the northern muriqui (Brachyteles hypoxanthus)

Social, ecological, and historical processes affect the genetic structure of primate populations, and therefore have key implications for the conservation of endangered species. The northern muriqui (Brachyteles hypoxanthus) is a critically endangered New World monkey and a flagship species for the conservation of the Atlantic Forest hotspot. Yet, like other neotropical primates, little is known about its population history and the genetic structure of remnant populations. We analyzed the mitochondrial DNA control region of 152 northern muriquis, or 17.6% of the 864 northern muriquis from 8 of the 12 known extant populations and found no evidence of phylogeographic partitions or past population shrinkage/expansion. Bayesian and classic analyses show that this finding may be attributed to the joint contribution of female-biased dispersal, demographic stability, and a relatively large historic population size. Past population stability is consistent with a central Atlantic Forest Pleistocene refuge. In addition, the best scenario supported by an Approximate Bayesian Computation analysis, significant fixation indices (Φ_ST = 0.49, Φ_CT = 0.24), and population-specific haplotypes, coupled with the extirpation of intermediate populations, are indicative of a recent geographic structuring of genetic diversity during the Holocene. Genetic diversity is higher in populations living in larger areas (>2,000 hectares), but it is remarkably low in the species overall (θ = 0.018). Three populations occurring in protected reserves and one fragmented population inhabiting private lands harbor 22 out of 23 haplotypes, most of which are population-exclusive, and therefore represent patchy repositories of the species'' genetic diversity. We suggest that these populations be treated as discrete units for conservation management purposes.     

Life history predicts risk of species decline in a stochastic world

Understanding what traits determine the extinction risk of species has been a long-standing challenge. Natural populations increasingly experience reductions in habitat and population size concurrent with increasing novel environmental variation owing to anthropogenic disturbance and climate change. Recent studies show that a species risk of decline towards extinction is often non-random across species with different life histories. We propose that species with life histories in which all stage-specific vital rates are more evenly important to population growth rate may be less likely to decline towards extinction under these pressures. To test our prediction, we modelled declines in population growth rates under simulated stochastic disturbance to the vital rates of 105 species taken from the literature. Populations with more equally important vital rates, determined using elasticity analysis, declined more slowly across a gradient of increasing simulated environmental variation. Furthermore, higher evenness of elasticity was significantly correlated with a reduced chance of listing as Threatened on the International Union for Conservation of Nature Red List. The relative importance of life-history traits of diverse species can help us infer how natural assemblages will be affected by novel anthropogenic and climatic disturbances.     

长喙毛茛泽泻的生活史特征及濒危机制

长喙毛茛泽泻(Ranalisma rostratum)是1种水生濒危植物,目前我国仅在湖南茶陵的湖里沼泽中生存有1个种群。在自然生境中,它在水深5～10 cm条件下生长良好,植株挺水。该植物以无性和有性两种方式生殖,无性繁殖体对种群的补充是保持自然种群大小的重要途径。虽然种子产量不是限制因素,但无性繁殖体和种子传播受限制、种子生活力及萌发率低、幼苗生长慢、在自然群落中竞争能力差、生境破坏很可能是导致这种植物濒危的重要原因。     

Life history traits of Pomatoschistus minutus in the Rhône Delta, France

Life history traits and migratory status of the Sand goby Pomatoschistus minutus were investigated in a brackish lagoon of the Rhône river Delta (Mediterranean Sea, south of France).     

Removing the threat of diclofenac to critically endangered Asian vultures

Veterinary use of the nonsteroidal anti-inflammatory (NSAID) drug diclofenac in South Asia has resulted in the collapse of populations of three vulture species of the genusGyps to the most severe category of global extinction risk. Vultures are exposed to diclofenac when scavenging on livestock treated with the drug shortly before death. Diclofenac causes kidney damage, increased serum uric acid concentrations, visceral gout, and death. Concern about this issue led the Indian Government to announce its intention to ban the veterinary use of diclofenac by September 2005. Implementation of a ban is still in progress late in 2005, and to facilitate this we sought potential alternative NSAIDs by obtaining information from captive bird collections worldwide. We found that the NSAID meloxicam had been administered to 35 captiveGyps vultures with no apparent ill effects. We then undertook a phased programme of safety testing of meloxicam on the African white-backed vultureGyps africanus, which we had previously established to be as susceptible to diclofenac poisoning as the endangered AsianGyps vultures. We estimated the likely maximum level of exposure (MLE) of wild vultures and dosed birds by gavage (oral administration) with increasing quantities of the drug until the likely MLE was exceeded in a sample of 40G. africanus. Subsequently, sixG. africanus were fed tissues from cattle which had been treated with a higher than standard veterinary course of meloxicam prior to death. In the final phase, ten Asian vultures of two of the endangered species(Gyps bengalensis,Gyps indicus) were dosed with meloxicam by gavage; five of them at more than the likely MLE dosage. All meloxicam-treated birds survived all treatments, and none suffered any obvious clinical effects. Serum uric acid concentrations remained within the normal limits throughout, and were significantly lower than those from birds treated with diclofenac in other studies. We conclude that meloxicam is of low toxicity toGyps vultures and that its use in place of diclofenac would reduce vulture mortality substantially in the Indian subcontinent. Meloxicam is already available for veterinary use in India.     

Apparent adult survival of the critically endangered Baltic Dunlin Calidris alpina schinzii during a period of strong population decline

Capsule: Apparent adult survival of the critically endangered Baltic Dunlin Calidris alpina schinzii, showed evidence of a decline between 1990 and 2006 from 0.817 to 0.650.

Aims: In Europe, declines in wet-grassland breeding waders have been attributed to changes in breeding habitat but long-term information on survival is rare. We examined whether adult survival of the Baltic Dunlin declined during a period of strong population decline.

Methods: We modelled apparent survival using Cormack–Jolly–Seber models and long-term capture–recapture data collected from a Danish population. We fitted models that constrained apparent adult survival with linear and quadratic trends, and compared them with constant and time dependent models to test whether survival declined during the study period.

Results: Models including linear and quadratic trends were most supported. However, the trend variables explained only 24–35% of observed temporal variance suggesting that a large portion of variation in survival remained undescribed. Model averaged estimates indicated a decline in adult survival from 0.817 to 0.650 between 1990 and 2006 with increased uncertainty towards the end.

Conclusion: Our results suggest that gradual long-term changes in adult survival may have contributed to the decline of the Baltic Dunlin.     

Diet of the critically endangered Seychelles Scops Owl,Otus insularis

The only data previously recorded on the diet of the critically endangered, endemic Seychelles Scops Owl, Otus insularis, is from the stomach contents of a few museum specimens and analysis of one pellet. Data are presented on more than 400 prey items identified from pellets and video recordings of provisioning at two nests. Pellets comprised exclusively of invertebrate remains: Orthoptera (64%), Coleoptera (14%), arachnids (11%) and other invertebrates (11%). Similarly, 111 (76%) of all items identified during 145 provisioning visits at two nests were invertebrates. Seventy-three (66%) were identified to morphospecies and comprised Orthoptera (93%), arachnids (4%) and Lepidoptera (3%). The diet of scops owls inhabiting areas of different altitudes (180-700m asl) was similar. Identification of prey taxa and species suggests that a significant amount of foraging takes place from foliage and on tree trunks, not just on the ground.     

Life history traits predict insect species responses to large herbivore overabundance: a multitaxonomic approach

There is increasing concern over the ecological impact of markedly increasing numbers of large herbivores (hereafter large herbivore overabundance) on forest ecosystems. To predict the ecological consequences of large herbivore overabundance, it is first necessary to understand how biological communities respond to large herbivore overabundance. Here, we examined the relationships between the life history traits of five insect taxonomic groups (moths, dung beetles, longicorn beetles, carabid beetles, and carrion beetles) and their responses to deer overabundance in Hokkaido, northern Japan. Insects were collected from three study sites: enclosure (20 deer/km²), control (10 deer/km²), and exclosure (0 deer/km²). The different taxonomic and functional insect species differed in their response to deer overabundance. The abundance (number of individuals) of longicorn beetles, dung beetles, and arbor-feeding moths was higher in the enclosure site than in the control site, whereas that of carabid beetles, carrion beetles, and herb- or shrub-feeding moths was higher in the control site than in the enclosure site. These results suggest that the type of food and the level of dependence on the understory are key traits determining insect sensitivity to deer overabundance. In addition, large or flightless species responded negatively to deer overabundance. Overall, this study demonstrated a significant change in insect communities following experimental deer overabundance, suggesting that large herbivore overabundance leads to the homogenization of biological communities. Unfortunately, because insects have diverse functions in forest ecosystems, such marked changes in both abundance and composition of insect communities will decrease ecosystem functions and resilience.     

Life history traits of the sea snake Emydocephalus annulatus,based on a 17-yr study

Although sea snakes are important predators in coral reef ecosystems and have undergone substantial population declines in some areas, we have little robust information on life histories of these animals. Based on a 17-yr mark–recapture study of turtle-headed sea snakes (Emydocephalus annulatus) in New Caledonia (> 1200 individuals marked), we can confidently allocate ages to 539 individuals (1–11 yr of age). Using data for those snakes, we describe patterns of growth and reproduction. Using the entire data set, we also estimate annual rates of survival. One to three large offspring (300 mm snout–vent length [SVL]) are born after a prolonged (8-month) gestation. The young snakes grow rapidly until they are about 2 yr old (500 mm SVL), after which growth slows, especially in males. Most females begin reproducing at 3 yr of age, and they produce a litter (typically of two offspring) in about 2 out of every 3 or 4 yr thereafter. Annual survival rates are around 70%, but some individuals live for more than a decade. Overall, the life history of this species involves rapid growth and early maturation, followed by low but sustained reproductive output. Despite their relatively recent evolutionary origin, hydrophiine sea snakes are remarkably diverse in life histories as well as in morphologies and diets. Hence, even closely related taxa may differ substantially in their vulnerability to threatening processes.

     

Evolution of biometric and life‐history traits in lizards (Gallotia) from the Canary Islands

The aim was to study as to how biometric and life‐history traits of endemic lacertids in the Canary Islands (genus Gallotia) may have evolved, and possible factors affecting the diversification process of this taxon on successively appearing islands have been deduced. To that end, comparative analyses of sexual dimorphism and scaling of different body, head and life‐history traits to body size in 10 species/subspecies of Gallotia have been carried out. Both Felsenstein's independent contrasts and Huey and Bennett's ‘minimum evolution’ analyses show that male and female snout‐vent length (SVL) changed proportionally (sexual size dimorphism not changing with body size) throughout the evolution of these lizards and all within‐sex biometric traits have changed proportionally to SVL. Life‐history traits (size at sexual maturity, clutch size, hatchling SVL and mass, and life span) are highly correlated with adult female body size, the first two being the only traits with a positive allometry to female SVL. These results, together with the finding that the slope of hatchling SVL to female SVL regression was lower than that of SVL at maturity to female SVL, indicates that larger females reach maturity at a larger size, have larger clutches and, at the same time, have relatively smaller hatchlings than smaller females. There was no significant correlation between any pair of life‐history traits after statistically removing the effect of body size. As most traits changed proportionally to SVL, the major evolutionary change has been that of body size (a ca. threefold change between the largest and the smallest species), that is suggested to be the effect of variable ecological conditions faced by founder lizards in each island.     

Life history invariants,age at maturity and the ferox trout

Summary Data on brown trout in Norway and on Arctic char in Norway, Iceland, Greenland or Canada are used to make three points about life-history invariants. First, invariants constructed from adaptive programmes of development that are conditioned on growth and mortality rates are more complicated than those constructed solely on the basis of dimensional analysis, but are more consistent with the data. Second, if one allows the possibility of escaping a size ceiling (e.g. by switching from planktivory to piscivory) ferox trout — brown trout that are exceptionally large and long lived — are predicted with the theory only if mortality is size dependent and the growth rate on food sources with different asymptotic sizes differs. Third, a successful empirical approach for finding life-history invariants can be more fully understood as the result of adaptive programmes of development.