Iskanje po repozitoriju

A+ | A- | | SLO | ENG

Povzetek: Textbook knowledge tells us that arachnids are a hyper diverse clade of chelicerates that have taken on terrestrial lifestyles. Original papers published in prestigious venues routinely reconstruct details of this purported single terrestrialization event that would have been followed by arachnid diversification on land. However, we are beginning to understand that arachnids are very likely paraphyletic; as such, Arachnida can only circumscribe an assemblage of chelicerates that live terrestrially. If so, arachnid terrestrialization may have taken several independent routes at different historic times. While the diversity and phylogeny of spiders, scorpions and harvestmen may be relatively well documented and understood, additional groups that we deem to be arachnids remain enigmatic and will likely continue to be more or less neglected after this Special Issue. We have here assembled examples of contemporary studies that include both original research as well as reviews focusing on “arachnids” and cover loosely defined biological subdisciplines of phylogenomics, biogeography, and evolution. The latter includes systematics, taxonomy, DNA barcoding, and trait evolution. In this editorial, I introduce the authors of these papers and their featured research, and through this narrative, I pose two questions. The first one is what is arachnology given that arachnids may not be monophyletic? The second question is where should our field be headed toward in the near future?
Ključne besede: biogeography, phylogeny, systematics, evolution, arachnology
Objavljeno v DiRROS: 06.08.2024; Ogledov: 27; Prenosov: 10
Celotno besedilo (197,54 KB)
Gradivo ima več datotek! Več...

Povzetek: Island systems provide excellent arenas to test evolutionary hypotheses pertaining to gene flow and diversification of dispersal-limited organisms. Here we focus on an orbweaver spider genus Cyrtognatha (Tetragnathidae) from the Caribbean, with the aims to reconstruct its evolutionary history, examine its biogeographic history in the archipelago, and to estimate the timing and route of Caribbean colonization. Specifically, we test if Cyrtognatha biogeographic history is consistent with an ancient vicariant scenario (the GAARlandia landbridge hypothesis) or overwater dispersal. We reconstructed a species level phylogeny based on one mitochondrial (COI) and one nuclear (28S) marker. We then used this topology to constrain a time-calibrated mtDNA phylogeny, for subsequent biogeographical analyses in BioGeoBEARS of over 100 originally sampled Cyrtognatha individuals, using models with and without a founder event parameter. Our results suggest a radiation of Caribbean Cyrtognatha, containing 11 to 14 species that are exclusively single island endemics. Although biogeographic reconstructions cannot refute a vicariant origin of the Caribbean clade, possibly an artifact of sparse outgroup availability, they indicate timing of colonization that is much too recent for GAARlandia to have played a role. Instead, an overwater colonization to the Caribbean in mid-Miocene better explains the data. From Hispaniola, Cyrtognatha subsequently dispersed to, and diversified on, the other islands of the Greater, and Lesser Antilles. Within the constraints of our island system and data, a model that omits the founder event parameter from biogeographic analysis is less suitable than the equivalent model with a founder event.
Ključne besede: biogeography, spiders
Objavljeno v DiRROS: 23.07.2024; Ogledov: 92; Prenosov: 72
Celotno besedilo (1,62 MB)
Gradivo ima več datotek! Več...

Povzetek: Dispersal ability can affect levels of gene flow thereby shaping species distributions and richness patterns. The intermediate dispersal model of biogeography (IDM) predicts that in island systems, species diversity of those lineages with an intermediate dispersal potential is the highest. Here, we tested this prediction on long-jawed spiders (Tetragnatha) of the Caribbean archipelago using phylogenies from a total of 318 individuals delineated into 54 putative species. Our results support a Tetragnatha monophyly (within our sampling) but reject the monophyly of the Caribbean lineages, where we found low endemism yet high diversity. The reconstructed biogeographic history detects a potential early overwater colonization of the Caribbean, refuting an ancient vicariant origin of the Caribbean Tetragnatha as well as the GAARlandia land-bridge scenario. Instead, the results imply multiple colonization events to and from the Caribbean from the mid-Eocene to late-Miocene. Among arachnids, Tetragnatha uniquely comprises both excellently and poorly dispersing species. A direct test of the IDM would require consideration of three categories of dispersers; however, long-jawed spiders do not fit one of these three a priori definitions, but rather represent a more complex combination of attributes. A taxon such as Tetragnatha, one that readily undergoes evolutionary changes in dispersal propensity, can be referred to as a ‘dynamic disperser’.
Ključne besede: Tetragnatha, dynamic disperser, intermediate dispersal model of biogeography, GAARlandia
Objavljeno v DiRROS: 19.07.2024; Ogledov: 81; Prenosov: 23
Povezava na datoteko

Povzetek: Reconstructing the origin and historical biogeography of the Austropotamobius torrentium is hampered by insufcient phylogeographic coverage of the Balkans and deep contradictions in previous molecular dating. The present work extends the phylogeographic coverage to Serbia, a country crucial for understanding the species southward dispersal. Our analysis revealed that the Southern Balkans lineage occurs in most of the country, the Central and southeastern Europe lineage is restricted to the southwest and northeast of the country, while a single population in the north of the country harbors the Lika and Dalmatia lineage, which was previously thought to be restricted to the northern-central Dinarides. Dataset expansion led to revised phylogenetic relationships, which indicated that the Apuseni lineage is not nested within Northern-central Dinarides lineages but arose after the most basal split within Austropotamobius torrentium. This ‘Apuseni frst’ phylogeny provides a new perspective for molecular dating, according to which the split between Austropotamobius pallipes and A. torrentium took place in the Late Oligocene, while the formation of the phyletic lineages and the dispersal from the Dinarides to Serbia occurred in the late Miocene and is probably associated with the complex and protracted process of disintegration of the Neogene freshwater lakes in southeastern Europe.
Ključne besede: Austropotamobius torrentium, Austropotamobius bihariensis, divergence time estimation conficts, historical biogeography, neogene lakes, Serbia
Objavljeno v DiRROS: 09.07.2024; Ogledov: 124; Prenosov: 99
Celotno besedilo (3,73 MB)
Gradivo ima več datotek! Več...

Povzetek: Introduction: Herbaceous plant species constitute an essential element of the flora of European beech (Fagus sylvatica) forests. There is increasing evidence that rapidly changing climate is likely to modify the spatial distribution of plant species. However, we lack understanding of the impact that climate change might have on beech forest herbs across the European continent. We investigated the possible effects of predicted increasing rates of global warming and altered precipitation regimes on 71 forest herbs closely associated with beech forests, but with varying biogeographic and climatic niche attributes. Methods: By using a total of 394,502 occurrence records and an ensemble of species distribution models (SDMs), we quantified the potential current distribution and future (2061-2080) range shifts in climatic suitability (expressed as occurrence probability, OP) according to two climate change scenarios (moderate SSP2-4.5 and severe SSP5-8.5). Results: Overall, precipitation of the warmest quarter and temperature seasonality were the most influential predictors in shaping current distribution patterns. For SSP5-8.5 scenario, all studied species experienced significant reductions (52.9% on average) in the total size of highly suitable areas (OP >0.75). However, the magnitude and directions of changes in the climatic suitability were highly species-specific; few species might even increase OP in the future, particularly in case of SSP2-4.5 scenario. The SDMs revealed the most substantial decline of climatic suitability at the trailing edges in southern Europe. We found that climatic suitability is predicted to show unidirectional northward shift and to move toward higher elevations. The gain/loss ratio was generally higher for narrow-ranged species compared to widespread taxa. Discussion: Our findings are contextualized with regards to potential confounding factors (dispersal limitation, microclimatic buffering) that may mitigate or accelerate climate change impacts. Given the low long-distance migration ability, many beech forest herbs are unlikely to track the velocity with which macroclimatic isotherms are moving toward higher latitudes, making this species group particularly vulnerable to climate change.
Ključne besede: species distribution modelling, global warming, range shift, climatic niche, biogeography, Europe
Objavljeno v DiRROS: 29.11.2023; Ogledov: 445; Prenosov: 233
Celotno besedilo (8,49 MB)
Gradivo ima več datotek! Več...