13 research outputs found
Climate drives community-wide divergence within species over a limited spatial scale: evidence from an oceanic island
Geographic isolation substantially contributes to species endemism on oceanic islands when speciation involves the colonisation of a new island. However, less is understood about the drivers of speciation within islands. What is lacking is a general understanding of the geographic scale of gene flow limitation within islands, and thus the spatial scale and drivers of geographical speciation within insular contexts. Using a community of beetle species, we show that when dispersal ability and climate tolerance are restricted, microclimatic variation over distances of only a few kilometres can maintain strong geographic isolation extending back several millions of years. Further to this, we demonstrate congruent diversification with gene flow across species, mediated by Quaternary climate oscillations that have facilitated a dynamic of isolation and secondary contact. The unprecedented scale of parallel species responses to a common environmental driver for evolutionary change has profound consequences for understanding past and future species responses to climate variation
Validation of an intrinsic groundwater pollution vulnerability methodology using a national nitrate database.
The importance of groundwater for potable supply, and the many sources of
anthropogenic contamination, has led to the development of intrinsic groundwater
vulnerability mapping. An Analysis of Co-Variance and Analysis of Variance are
used to validate the extensively applied UK methodology, based upon nitrate
concentrations from 1,108 boreholes throughout England and Wales. These largely
confirm the current aquifer and soil leaching potential classifications and
demonstrate the benefits of combining soil and low permeability drift
information. European legislation such as the Water Framework Directive will
require more dynamic assessments of pollutant risk to groundwater. These results
demonstrate that a number of improvements are required to future intrinsic
groundwater vulnerability methodologies. The vertical succession of geological
units must be included, so that non-aquifers can be zoned in the same way as
aquifers for water supply purposes, while at the same time recognising their
role in influencing the quality of groundwater in deeper aquifers.
Classifications within intrinsic vulnerability methodologies should be based
upon defined diagnostic properties rather than expert judgement. Finally the
incorporation into groundwater vulnerability methodologies of preferential flow
in relation to geological deposits, soil type and land management practices
represents a significant, but important, future challenge
Recent geospatial dynamics of Terceira (Azores, Portugal) and the theoretical implications for the biogeography of active volcanic islands
Ongoing work shows that species richness patterns on volcanic oceanic islands are shaped by surface area changes driven by longer time scale (>1 ka) geological processes and natural sea level fluctuations. A key question is: what are the rates and magnitudes of the forces driving spatial changes on volcanic oceanic islands which in turn affect evolutionary and biogeographic processes? We quantified the rates of surface-area changes of a whole island resulting from both volcanogenic flows and sea level change over the last glacial-interglacial (GI) cycle (120 ka) for the volcanically active island of Terceira, (Azores, Macaronesia, Portugal). Volcanogenic activity led to incidental but long-lasting surface area expansions by the formation of a new volcanic cone and lava-deltas, whereas sea level changes led to both contractions and expansions of area. The total surface area of Terceira decreased by as much as 24% per time step due to changing sea levels and increased by 37% per time step due to volcanism per time step of 10 ka. However, while sea levels nearly continuously changed the total surface area, volcanic activity only impacted total surface area during two time steps over the past 120 ka. The surface area of the coastal and lowland region (here defined as area [removed
Global change in microcosms: Environmental and societal predictors of land cover change on the Atlantic Ocean Islands
10.1016/j.ancene.2020.100242Anthropocene30100242-10024
Correspondence : Smith (William) and Engelmann (George), 1876.
Smith, (William) to Engelmann, 187
Island biodiversity conservation needs palaeoecology
The discovery and colonization of islands by humans has invariably resulted in their widespread ecological transformation. The
small and isolated populations of many island taxa, and their evolution in the absence of humans and their introduced taxa,
mean that they are particularly vulnerable to human activities. Consequently, even the most degraded islands are a focus for
restoration, eradication, and monitoring programmes to protect the remaining endemic and/or relict populations. Here, we
build a framework that incorporates an assessment of the degree of change from multiple baseline reference periods using
long-term ecological data. The use of multiple reference points may provide information on both the variability of natural systems
and responses to successive waves of cultural transformation of island ecosystems, involving, for example, the alteration
of fire and grazing regimes and the introduction of non-native species. We provide exemplification of how such approaches can
provide valuable information for biodiversity conservation managers of island ecosystems