Neolithic People Purposefully Introduced Red Deer to the Scottish Islands

Colonization of the Scottish islands via long-distance Neolithic transport of red deer (Cervus elaphus)

Authors:

Stanton et al

Abstract:

Red deer (Cervus elaphus) have played a key role in human societies throughout history, with important cultural significance and as a source of food and materials. This relationship can be traced back to the earliest human cultures and continues to the present day. Humans are thought to be responsible for the movement of a considerable number of deer throughout history, although the majority of these movements are poorly described or understood. Studying such translocations allows us to better understand ancient human–wildlife interactions, and in the case of island colonizations, informs us about ancient human maritime practices. This study uses DNA sequences to characterise red deer genetic diversity across the Scottish islands (Inner and Outer Hebrides and Orkney) and mainland using ancient deer samples, and attempts to infer historical colonization events. We show that deer from the Outer Hebrides and Orkney are unlikely to have originated from mainland Scotland, implying that humans introduced red deer from a greater distance. Our results are also inconsistent with an origin from Ireland or Norway, suggesting long-distance maritime travel by Neolithic people to the outer Scottish Isles from an unknown source. Common haplotypes and low genetic differentiation between the Outer Hebrides and Orkney imply common ancestry and/or gene flow across these islands. Close genetic proximity between the Inner Hebrides and Ireland, however, corroborates previous studies identifying mainland Britain as a source for red deer introductions into Ireland. This study provides important information on the processes that led to the current distribution of the largest surviving indigenous land mammal in the British Isles.

Evidence of Invasive Species Introduced by Native Americans to the West Indies

Sr and Pb isotopic investigation of mammal introductions: Pre-Columbian zoogeographic records from the Lesser Antilles, West Indies

Authors:

Giovas et al

Abstract:

Recent efforts to reconstruct the anthropogenic paleozoogeography of introduced Neotropical mammals in the West Indies provide new analytical foundations for evaluating island and continental human interaction, exchange, colonization, and animal management. Key questions in these investigations concern the timing, source, population viability, and environmental impact of continental faunal translocations in the pre-Columbian insular Caribbean. To investigate these issues we analyzed 87Sr/86Sr, 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb isotope ratios from environmental samples and agouti (Dasyprocta sp.) and opossum (Didelphis cf. marsupialis) remains from Ceramic Age (500 BC – AD 1500) archaeological deposits on the islands of Nevis, Carriacou, and Mustique in the Lesser Antilles. This study was undertaken to assess the suitability of agouti and opossum tooth enamel for isotopic analysis, characterize local bioavailable Sr and Pb isotope ratios, and distinguish possible local and non-local agouti and opossum individuals. We demonstrate large intra-island variability in bioavailable Sr across multiple islands giving rise to potential equifinality in identifying taxa of non-local origin. We argue, consequently, for the necessity of comprehensive environmental sampling at the island scale to better define the range and mean of bioavailable Sr for a given locale. Our results further show that Pb isotope analysis of sampled taxa is problematized to varying degrees by modern anthropogenic lead contamination, even for well-preserved ‘clean’ tooth enamel from intact archaeological specimens and raise questions about the utility of this method for evaluating past animal translocations and the use of small mammals for establishing local bioavailable Pb. Despite these results, Sr data are sound and, in combination with vetted Pb ratios, indicate that agouti and opossum were established as living populations on Carriacou and Nevis as early as ca. AD 600/800, and possibly earlier. These results establish baseline data for evaluating exchange networks involving living animals or their parts, potential captive management of agouti and opossum, and the ecological impact of exotic species during the Pre-Columbian era in the West Indies.

Was Tyrannosaurus an Invasive Species?

Tyrannosaurus rex, king of the dinosaur age, wasn't a North American native as many experts had previously thought, a new study suggests.

Instead, the giant tyrannosaur was likely an invasive species from Asia that dispersed into western North America once the opportunity presented itself, paleontologists said.

"It's possible that T. rex was an immigrant species from Asia," said study co-researcher Steve Brusatte, a paleontologist at the University of Edinburgh in Scotland. But he cautioned that the finding isn't necessarily a "slam dunk," and that more research is needed to say for sure.

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Global Warming Will Have Weird Effects on Invasive Species

Rising temperatures may be seen as universally beneficial for non-native species expanding northward, but a Dartmouth College study suggests a warmer world may help some invaders but hurt others depending on how they and native enemies and competitors respond.

The study, which sheds light on the uncertain relationship between climate change and invasive species, appears in the journal Ecology. A PDF of the study is available on request.

Climate change and invasive species rank among the largest predicted threats to global ecosystems over the next century, but they are typically treated independently. To date, research focusing on the connection between these two threats has primarily focused on the idea that species from lower latitudes, which typically experience warmer temperatures than those in higher latitude ecosystems, will perform better at higher latitudes as temperatures warm. The Dartmouth study focuses instead on how a trait common among certain invasive species -- benefiting from "enemy release" -- can be influenced by changes in temperatures. The ''enemy release'' hypothesis holds that certain invading species succeed because they escape from their natural enemies -- pathogens, parasites, herbivores and predators -- in their native habitat. The Dartmouth study's approach takes into account that invading species are attempting to establish in locations where other species already exist, and the interactions with these existing species are important to consider.

The researchers conducted a six-week experiment manipulating the presence of sunfish and water temperature using two non-native and native crustacean zooplankton. They found that increases in water temperature favored the non-native crustacean due its faster growth rate at higher temperatures, as well as the fact that sunfish predators of both crustaceans eat more at higher temperatures. The sunfish's increased appetite disproportionally benefits the non-native crustacean because it has more effective defenses against fish predation -- hence its "release" from this particular enemy -- than the native crustacean.

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Global Warming Will NOT Bring Spring Forward for Southern Invasive Species

Global warming is generally expected to bring spring forward but, as a new study at Ludwig-Maximilians-Universitaet (LMU) in Munich shows, a concomitant influx of plant species from warmer southern latitudes could counteract this effect.

Climate change is already clearly discernible in our part of the world. Data from local weather stations indicate that the average temperature in the Munich region has risen by 1.5°C over the past century. LMU biologist Professor Susanne Renner and her research group have now looked at the effects of this warming trend on the timing of leaf emergence ("leaf-out") in a broad range of shrubs and trees.

The inducers of leaf-out

"It is widely believed that warmer temperatures will extend the growing season and that leaf-out in our flora will occur at progressively earlier times in the year. However, whether air temperature or day-length is the dominant factor determining the date of leaf-out is actually known for very few of the thousands of species of trees and shrubs," says Renner. As Director of Munich's Botanic Garden, she was in a position to remedy this situation.

Some 16,000 plant species from diverse climate zones are cultivated in the Garden, and Renner and her doctoral student Constantin Zohner have taken advantage of this unique resource to monitor the timing of leaf-out in nearly 500 different species of woody plants. "Such a comprehensive phenological study has never been undertaken before," says Renner. Temperature and day-length are the primary triggers of leaf development, and selective forces during the course of evolution have determined which signal is actually used in a given species. The results of the new study show that, in many woody plants that thrive in warmer southern climes, day-length acts as a safety barrier so that these trees don't risk having their leaves damaged by late frosts – and increased temperature does not override this barrier.

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Is The "Anthropocene" Going to INCREASE Biodiversity?!

Human activity changes the environment, as last week’s release of a report by the Intergovernmental Panel on Climate Change reminds us. But not all change is bad. One way in which animals and plants respond to warming temperatures, for example, is to move beyond their historical distributions, just as they do when they are transported to new regions by humans. The response of people who find themselves ‘invaded’ by such ‘displaced’ species is often irrational. Deliberate persecution of the new — just because it is new — is no longer sustainable in a world of rapid global change.

It is true that some invasive species damage ecosystems and can eradicate resident species. As a result, the European Commission, for example, is planning laws to control the ‘adverse’ impacts of species introduced through human activities, albeit without quite saying how those impacts should be defined. But the same process can also increase ecological diversity. On average, less than one native species dies out for each introduced species that arrives. Britain, for instance, has gained 1,875 established non-native species without yet losing anything to the invaders.

Human development — dubbed the age of the Anthropocene — boosts biodiversity in other ways too.

eyebrow raising link.

Whither Invasive Competion: How Right is Benton Then?

Plant invasions and extinction debts

Authors:

1. Benjamin Gilbert (a,b)
2. Jonathan M. Levine (b,c)

Affiliations:

a. Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 3B2;

b. Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106

c. Institute for Integrative Biology, Eidgenössiche Technische Hochschule Zurich, 8092 Zurich, Switzerland

Abstract:

Whether introduced species invasions pose a major threat to biodiversity is hotly debated. Much of this debate is fueled by recent findings that competition from introduced organisms has driven remarkably few plant species to extinction. Instead, native plant species in invaded ecosystems are often found in refugia: patchy, marginal habitats unsuitable to their nonnative competitors. However, whether the colonization and extinction dynamics of these refugia allow long-term native persistence is uncertain. Of particular concern is the possibility that invasive plants may induce an extinction debt in the native flora, where persistence over the short term masks deterministic extinction trajectories. We examined how invader impacts on landscape structure influence native plant persistence by combining recently developed quantitative techniques for evaluating metapopulation persistence with field measurements of an invaded plant community. We found that European grass invasion of an edaphically heterogeneous California landscape has greatly decreased the likelihood of the persistence of native metapopulations. It does so via two main pathways: (i) decreasing the size of native refugia, which reduces seed production and increases local extinction, and (ii) eroding the dispersal permeability of the matrix between refugia, which reduces their connectivity. Even when native plant extinction is the deterministic outcome of invasion, the time to extinction can be on the order of hundreds of years. We conclude that the relatively short time since invasion in many parts of the world is insufficient to observe the full impact of plant invasions on native biodiversity.

Or is he?