High tropical net diversification drives the New World latitudinal gradient in palm (Arecaceae) species richness

Aim Species richness exhibits striking geographical variation, but the processes that drive this variation are unresolved. We investigated the relative importance of two hypothesized evolutionary causes for the variation in palm species richness across the New World: time for diversification and evolutionary (net diversification) rate. Palms have a long history in the region, with the major clades diversifying during the Tertiary (65–2 Ma). Location Tropical and subtropical America (34° N–34° S; 33–120° W). Methods Using range maps, palm species richness was estimated in a 1° × 1° grid. Mean lineage net diversification was estimated by the mean phylogenetic root distance (MRD), the average number of nodes separating a species from the base of the palm phylogeny for the species in each grid cell. If evolutionary rate limits richness, then richness should increase with MRD. If time limits richness, then old, relict species (with low root distance) should predominantly occur in long‐inhabited and therefore species‐rich areas. Hence, richness should decrease with MRD. To determine the influence of net diversification across different time frames, MRD was computed for subtribe, genus and species levels within the phylogeny, and supplemented with the purely tip‐level measure, mean number of species per genus (MS/G). Correlations and regressions, in combination with eigenvector‐based spatial filtering, were used to assess the relationship between species richness, the net diversification measures, and potential environmental and geographical drivers. Results Species richness increased with all net diversification measures. The regression models showed that richness and the net diversification measures increased with decreasing (absolute) latitude and, less strongly, with increasing energy/temperature and water availability. These patterns therefore reflect net diversification at both deep and shallow levels in the phylogeny. Richness also increased with range in elevation, but this was only reflected in the MS/G pattern and therefore reflects recent diversification. Main conclusions The geographical patterns in palm species richness appear to be predominantly the result of elevated net diversification rates towards the equator and in warm, wet climates, sustained throughout most of the Tertiary. Late‐Tertiary orogeny has caused localized increases in net diversification rates that have also made a mark on the richness pattern.     

杉木远交亲本群体遗传多样性研究

借助ISSR分子标记技术,对杉木和侧柏远交亲本群体的遗传多样性进行了研究,采用国际上流行的软件（PopGENE）进行数据处理,获得如下结果：(1)群体多态性位点百分率为88.2%;(2)Nei’s基因多样性指数平均值为0.399 7;(3)Shannon信息指数多样性数为0.582 4;(4)群体内亲本间的平均遗传距离为0.669 8,变幅为(0.069 0,1.609 4),其变异系数为69.19%。经与国内外同类研究结果比较分析后认定:杉木远交亲本群体具有较高的遗传多样性,具有较大的改良潜力,由其衍生的生产群体亦具有较宽的生态适应性。     

Gene flow among native bush rat,Rattus fuscipes (Rodentia: Muridae), populations in the fragmented subtropical forests of south‐east Queensland

Abstract Many natural populations in areas of continuous habitat exhibit some form of local genetic structure. Anthropogenic habitat fragmentation can also strongly influence the dynamics of gene flow between populations. We used eight microsatellite markers to investigate the population genetic structure of an abundant forest species, the Australian bush rat (Rattus fuscipes), in the subtropical forests of south‐east Queensland. Five sites were sampled, allowing pairwise comparisons within continuous habitat and across clearings. Weak, but significant population differentiation and a significant pattern of isolation by distance was detected over the small scale (<10 km) of this study. Fine‐scale analysis at a single site (<1 km) showed a significant correlation between individual female genetic distance and geographical distance, but no similar pattern among male individuals. There was no evidence of increased population differentiation across clearings relative to comparisons within continuous forest. This was attributed to dispersal within corridors of remnant and revegetated habitat between the forested areas. We concluded that an inherently restricted dispersal ability, female philopatry and natural habitat heterogeneity play an important part in the development of genetic structure among populations of R. fuscipes. It is important to understand the relationship between landscape features and the pattern of gene flow among continuous populations, as this allows us to predict the impact of fragmentation on natural populations.     

Waterbird responses to regular passage of a birdwatching tour boat: Implications for wetland management

Participation in outdoor recreation can increase support for wildlife conservation, but may also disturb wildlife. We examined responses of wintering waterbirds to the regular passage of a small boat specifically dedicated to birdwatching tours in a coastal Ramsar site in northern Spain. Disturbances were measured during two separate periods: 2006–2008 and 2012–2015. Incidence and magnitude of disturbance events were compared by grouping species based on their interest to birders (target vs. non-target) and compared across sectors of the tour route. Flight-initiation distances (FID) were used to estimate species-specific buffer zones, which can be used to manage recreational disturbance to waterbirds. We further examined relationships between species-specific traits and FID, time flying, and distance flying following disturbance. A single boat tour disturbed on average 0.3% of non-target and 2.8% of target wintering bird populations within the wetland, with the effect being more pronounced on target species due to their smaller populations. Wing loading was positively associated with distance flying after disturbance. Based on measured FIDs, we calculated an overall buffer zone for all species of 100 m, and species-specific buffer zones ranging from 41 to 211 m. Disturbance incidence and the number of birds disturbed per tour were both greatest in narrow tidal channels (<200 m), where boats were forced to pass within 100 m of waterbirds. We urge caution in allowing boat passage through tidal channels in which boat operators cannot effectively maintain recommended buffer zones between their boat and waterbirds.     

Seed dispersal kernel of the largest surviving megaherbivore—the African savanna elephant

Owing to the late Pleistocene extinctions, the megafauna of Europe, Australia and the Americas disappeared, and with them the dispersal service they offered megafaunal fruit. The African savanna elephant, the largest remaining megaherbivore, offers valuable insights into the seed dispersal services provided by extinct megafauna in prehistoric times. Elephant seed dispersal studies have for the most part concentrated on African and Asian forest elephants. African savanna elephants are morphologically distinct from their forest counterparts. Like the forest elephants they consume large quantities of fruit from a large number of tree species. Despite this little is known of the savanna trees that rely on elephants for their dispersal or the spatial scale at which these seeds are dispersed. We combined information from feeding trials conducted on four park elephants with field telemetry data from 38 collared elephants collected over an 8‐year period in APNR/Kruger National Park to assess the seed dispersal service provided by savanna elephants. This study provides the first detailed account of the spatial scale at which African savanna elephants disperse seeds. Our mechanistic model predicts that 50 percent of seeds are carried over 2.5 km, and distances up to 65 km are achievable in maximum gut passage time. These findings suggest the savanna elephant as the longest distance terrestrial vertebrate disperser yet investigated. Maintaining their ecological role as a seed disperser may prove a significant factor in the conservation of large‐fruited tree diversity within the savannas. These results suggest that extinct megafauna offered a functionally unique dispersal service to megafaunal fruit.     

Partitioning the effects of isolation by distance,environment, and physical barriers on genomic divergence between parapatric threespine stickleback

Genetic divergence between populations is shaped by a combination of drift, migration, and selection, yielding patterns of isolation‐by‐distance (IBD) and isolation‐by‐environment (IBE). Unfortunately, IBD and IBE may be confounded when comparing divergence across habitat boundaries. For instance, parapatric lake and stream threespine stickleback (Gasterosteus aculeatus) may have diverged due to selection against migrants (IBE), or mere spatial separation (IBD). To quantitatively partition the strength of IBE and IBD, we used recently developed population genetic software (BEDASSLE) to analyze partial genomic data from three lake‐stream clines on Vancouver Island. We find support for IBD within each of three outlet streams (unlike prior studies of lake‐stream stickleback). In addition, we find evidence for IBE (controlling for geographic distance): the genetic effect of habitat is equivalent to geographic separation of ～1.9 km of IBD. Remarkably, of our three lake‐stream pairs, IBE is strongest where migration between habitats is easiest. Such microgeographic genetic divergence would require exceptionally strong divergent selection, which multiple experiments have failed to detect. Instead, we propose that nonrandom dispersal (e.g., habitat choice) contributes to IBE. Supporting this conclusion, we show that the few migrants between habitats are a nonrandom subset of the phenotype distribution of the source population.     

Seasonal migration strategies of Common Ringed Plovers Charadrius hiaticula

How individual birds schedule their movements and use different sites during the non‐breeding season are fundamental issues in avian migration ecology, and studies have often revealed strong seasonal variation in such strategies. Using geolocators we tracked Common Ringed Plovers Charadrius hiaticula from northern Norway to West Africa and back to assess whether there were differences in migratory speed, duration and stopover use between autumn and spring migration and whether birds used multiple sites during the non‐breeding season. Although the pace of migration was similar between autumn and spring, the length of flight bouts and duration of the preceding stopovers were positively correlated only in autumn. Four of five birds showed a marked southward movement in mid‐winter.     

Spatial ecology of jaguars,pumas, and ocelots: a review of the state of knowledge

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