A survey was done to estimate margay abundance and activity in the context of high forest loss rates from avocado plantations for the temperate forest region of Michoacán state. Camera trap surveys ...were conducted from November 2015 to April 2020, recording 21 Margay detections of seven individuals. The capture rate ranged from 0.09 to 0.83 records/100 trap nights. The mean temporal density was 0.12 ind./km
, with an activity peak between 04:00 and 05:00 h. The Margay could serve as indicator species for restoration and forest conservation initiatives.
Abstract
Lower Central America is an important area to study recent population history and diversification of Neotropical species due to its complex and dynamic geology and climate. Phylogeographic ...studies in this region are few in comparison with other regions and even less for tree species. The aim of the present study was to characterize the phylogeographic structure in 2 partially co-distributed endemic oak species (Quercus costaricensis and Q. bumelioides) of the Costa Rican mountains using chloroplast short sequence repeats (cpSSRs), and to test for the effect of geological and palaeoclimatic processes on their population history. Genetic diversity and structure, haplotype networks, patterns of seed-mediated gene flow and historical demography were estimated for both species. Results suggested contrasting patterns. Quercus costaricensis exhibited high values of genetic diversity, a marked phylogeographic structure, a north-to-south genetic diversity gradient and evidence of a demographic expansion during the Quaternary. Quercus bumelioides did not show significant genetic structure and the haplotype network and historical demography estimates suggested a recent population expansion probably during the Pleistocene-Holocene transition. The phylogeographic structure of Q. costaricensis seems to be related to Pleistocene altitudinal migration due to its higher altitudinal distribution. Meanwhile, historical seed-mediated gene flow through the lower altitudinal distribution of Q. bumelioides may have promoted the homogenization of genetic variation. Population expansion and stable availability of suitable climatic areas in both species probably indicate that palaeoclimatic changes promoted downwards altitudinal migration and formation of continuous forests allowing oak species to expand their distribution into the Panamanian mountains during glacial stages.
While hybridization and introgression can have a strong adaptive importance, it can impede divergence of species.
Quercus magnoliifolia
and
Q. resinosa
are two endemic oak species distributed across ...the Mexican highlands. These species diverged ecological and morphologically; however, no nuclear genetic differentiation is evident. In this study, we determined the mechanisms that shape patterns of genetic variation and establish the role of migration and hybridization in the evolutionary history of these two oak species. To do this, Bayesian approaches were used for inference on migration rates and directionality and timing of divergence between species using chloroplast microsatellites. We then integrated species distribution models to infer the geographic distribution of
Q. magnoliifolia
and
Q. resinosa
during Last Interglacial, Last Glacial Maximum, and Mid-Holocene time frames. We failed in distinguishing a unique genetic composition for each species. Chloroplast differentiation was more congruent with geography than the taxonomic status of each species. Our study revealed that after the divergence (
c
. 10 Mya) of these two oak species, high rates of introgression took place at the end of the Pleistocene. Furthermore, past distribution models predicted that
Q. magnoliifolia
and
Q. resinosa
have likely been in sympatry presumable since Last Glacial Maximum and
Q. resinosa
probably expanded geographically towards its current distribution around Mid-Holocene. This expansion was supported by testing migration models, suggesting recent establishment of
Q. resinosa
to the north of Trans-Mexican Volcanic Belt. We hypothesized that after
Q. magnoliifolia
and
Q. resinosa
diverged, colonization events followed by hybridization between oaks and long-distance seed dispersal occurred, explaining the present-day patterns of distribution of chloroplast diversity. We propose that divergence of species remains mainly on loci under natural selection, providing evidence on the “porous” nature of species boundaries among oaks.
The northern Neotropical region is characterized by a heterogeneous geological and climatic history. Recent studies have shown contrasting patterns regarding the role of geographic elements as ...barriers that could have determined phylogeographic structure in various species. Recently, the phylogeography and biogeography of
Quercus
species have been studied intensively, and the patterns observed so far suggest contrasting evolutionary histories for Neotropical species in comparison with their Holarctic relatives. The goal of this study was to describe the phylogeographic structure of two Neotropical oak species (
Quercus insignis
and
Quercus sapotifolia
) in the context of the geological and palaeoclimatic history of the northern Neotropics. Populations through the distribution range of both species were collected and characterized using nine chloroplast DNA microsatellite loci. Both oak species showed high levels of genetic diversity and strong phylogeographic structure. The distribution of genetic variation in
Q. insignis
suggested an influence of two major barriers, the Isthmus of Tehuantepec and the Nicaraguan Depression, while
Q. sapotifolia
exhibited a genetic structure defined by the heterogeneity of the Chortis highlands. The haplotype networks of both species indicated complex histories, suggesting that colonization from the Sierra Madre de Chiapas to central Mexico and from the north of the Nicaraguan Depression to the Costa Rican mountains may have occurred during different stages, and apparently more than one time. In conclusion, the phylogeographic structure of Neotropical oak species seems to be defined by a combination of geological and climatic events.
Premise
Phylogeographical studies are fundamental for understanding factors that influence the spatial distribution of genetic lineages within species. Population expansions and contractions, ...distribution shifts, and climate changes are among the most important factors shaping the genetic compositions of populations.
Methods
We investigated the phylogeography of an endemic oak, Quercus mexicana (Fagaceae), which has a restricted distribution in northeastern Mexico along the Sierra Madre Oriental and adjacent areas. Nuclear and chloroplast DNA microsatellite markers were used to describe the genetic diversity and structure of 39 populations of Q. mexicana along its entire distribution area. We tested whether population expansion or contraction events influenced the genetic diversity and structure of the species. We also modeled the historical distributional range of Q. mexicana (for the Mid Holocene, the Last Glacial Maximum, and the Last Interglacial) to estimate the extent to which climate fluctuations have impacted the distribution of this oak species.
Results
Our results revealed high genetic diversity and low genetic structure in Q. mexicana populations. Ecological niche models suggested historical fluctuations in the distributional range of Q. mexicana. Historical range changes, gene flow, and physical barriers seem to have played an important role in shaping the phylogeographic structure of Q. mexicana.
Conclusions
Our study indicates that the genetic structure of Q. mexicana may have been the result of responses of oak trees not only to heterogeneous environments present in the Sierra Madre Oriental and adjacent areas, but also to elevational and latitudinal shifts in response to climate changes in the past.
The climatic and geological changes that occurred during the Quaternary, particularly the fluctuations during the glacial and interglacial periods of the Pleistocene, shaped the population demography ...and geographic distribution of many species. These processes have been studied in several groups of organisms in the Northern Hemisphere, but their influence on the evolution of Neotropical montane species and ecosystems remains unclear. This study contributes to the understanding of the effect of climatic fluctuations during the late Pleistocene on the evolution of Andean mountain forests. First, we describe the nuclear and plastidic DNA patterns of genetic diversity, structure, historical demography, and landscape connectivity of Quercus humboldtii, which is a typical species in northern Andean montane forests. Then, these patterns were compared with the palynological and evolutionary hypotheses postulated for montane forests of the Colombian Andes under climatic fluctuation scenarios during the Quaternary. Our results indicated that populations of Q. humboldtii have high genetic diversity and a lack of genetic structure and that they have experienced a historical increase in connectivity from the last glacial maximum (LGM) to the present. Furthermore, our results showed a dramatic reduction in the effective population size followed by an expansion before the LGM, which is consistent with the results found by palynological studies, suggesting a change in dominance in Andean forests that may be related to ecological factors rather than climate change.
This study describes the nuclear and plastidic DNA patterns of genetic diversity, structure, historical demography, and landscape connectivity of Quercus humboldtii. We found a high population genetic diversity, lack of genetic structure, and evidence of a demographic expansion predating the LGM
We studied populations of Stenocereus pruinosus throughout Mexico, a species important for its edible fruit. The Tehuacán Valley is setting of ancient and the currently most active management of S. ...pruinosus; we hypothesized Tehuacán as the original area of domestication of S. pruinosus and expected to find there its highest genetic variation and original source of genes of cultivated plants. Through nuclear microsatellite loci we studied spatial distribution of genetic variation and population differentiation. We sampled wild and managed populations of the Central-western (Tehuacán, Central Valleys and Tehuantepec, Oaxaca), north-eastern (Huasteca) and south-eastern (Chiapas) regions. Differences among regions and populations were compared through homogeneity and exact test for F IS , AMOVA, Bayesian analysis, and genetic barriers. A niche analysis allowed corroborating taxonomic identity of populations. The highest genetic diversity was in Tehuantepec (H E = 0.841), decreasing towards the extremes of distribution (H E = 0.242 in Huasteca, H E = 0.254 in Chiapas). Genetic structure is significantly high among populations and regional groups, differentiating one group formed by northern and southern populations and other formed by populations of the Central-western region. Differences among groups suggested that populations from Huasteca could be species different to S. pruinosus, but the niche analysis did not support such hypothesis. Populations from Tehuantepec were different but genetically interconnected with those of Tehuacán. Tehuantepec is the main reservoir of genetic diversity of wild populations of S. pruinosus, but Tehuacán is the principal current area of domestication of S. pruinosus and probably where its domestication originated. Conclusions would be stronger by analyzing DNAc lineages.
Post-2020 goals overlook genetic diversity Laikre, Linda; Hoban, Sean; Bruford, Michael W ...
Science (American Association for the Advancement of Science),
03/2020, Letnik:
367, Številka:
6482
Journal Article
Mixed bird flocks are groups of individuals from different species that travel and forage together. Such groups are common in several bird communities around the world. We present species composition ...and activity patterns of mixed bird flocks in a region of the Central Andes of Colombia. We compared the number of species per flock, as well as the number of flocks among 3 different habitats. We tested hypotheses concerning the flocks daily activity and the co-occurrences of species within them. We recorded 75 species, and the species number per flock varied from 4 to 21. Our data suggest that habitat affects the number of flocks but not their species number, and that the activity of flocks is similar throughout the day. In addition, the association of birds in flocks is affected by interspecific facilitation, with some species co-occurrences found more times than expected by chance. We hypothesize that some tanager species could have a role in flock cohesion. We witnessed 2 predator attacks upon flocks, a number of agonistic interactions among flock members, and squirrels following bird flocks. Our results meet some general patterns described for mixed bird flocks.
In this study we assessed tree species richness, density, and composition patterns along a gradient of urbanization of a megacity. Our results show that total, native, and exotic tree densities were ...highest in green areas where larger spaces are considered for greening purposes. Conversely, total, native, and exotic tree species richness were highest in land uses with intermediate levels of urban development (residential, residential-commercial areas). Not finding highest tree species richness in less developed urban areas suggests that cultural factors may shape the array of species that are planted within cities. Supporting this, tree composition analyses showed that green areas are comprised of different tree species when compared to the rest of the studied urban land uses. Thus, our results suggest that, to increase the ecological quality of cities, residents and managers should be encouraged to select a greater variety of trees to promote heterogeneous green areas.
PDF
