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1.
Peter Alpert 《Biological invasions》2006,8(7):1523-1534
Introduced species, those dispersed outside their natural ranges by humans, now cause almost all biological invasions, i.e.,
entry of organisms into habitats with negative effects on organisms already there. Knowing whether introduction tends to give
organisms specific ecological advantages or disadvantages in their new habitats could help understand and control invasions.
Even if no specific species traits are associated with introduction, introduced species might out-compete native ones just
because the pool of introduced species is very large (“global competition hypothesis”). Especially in the case of intentional
introduction, high initial propagule pressure might further increase the chance of establishment, and repeated introductions
from different source populations might increase the fitness of introduced species through hybridization. Intentional introduction
screens species for usefulness to humans and so might select for rapid growth and reproduction or carry species to suitable
habitats, all which could promote invasiveness. However, trade offs between growth and tolerance might make introduced species
vulnerable to extreme climatic events and cause some invasions to be transient (“reckless invader hypothesis”). Unintentional
introduction may screen for species associated with human-disturbed habitats, and human disturbance of their new habitats
may make these species more invasive. Introduction and natural long-distance dispersal both imply that species have neither
undergone adaptation in their new habitats nor been adapted to by other species there. These two characteristics are the basis
for many well-known hypotheses about invasion, including the “biotic resistance”, “enemy release”, “evolution of increased
competitive ability” and “novel weapon” hypotheses, each of which has been shown to help explain some invasions. To the extent
that biotic resistance depends upon local adaption by native species, altering selection pressures could reduce resistance
and promote invasion (“local adaptation hypothesis”), and restoring natural regimes could reverse this effect. 相似文献
2.
The paper brings data set of seed reproduction of about 500 wild herbaceous species of Central Europe and presents a number
of produced seeds in a new way. Number of seeds — reproductive capacity of a population (RCP) was defined as a number of seeds
produced by one species per 1 m2 at its one-hundred-per-cent cover per one season. About 23% of seed weight variability and about 26% of variability in RCP
were explainable on a family level. The trade-off between RCP and seed weight was confirmed both within families and also
among families. Both characteristics had higher variability on a family level and on lower taxonomic levels than on subclass
and class levels. Species with an annual life cycle have a larger number of seeds than perennials. Geophytes and species without
lateral spread have a tendency to produce a large amount of relatively weighty seeds in comparison to other life forms, and
to species with vegetative lateral spread. Species with seeds dispersed by wind usually have a large number of lightweight
seeds. Multivariate analyses confirmed some tendencies of reproductive traits which correspond to the definition of C-, S-,
R- strategies by Grime — “verification” of the RCP as ecological trait. The R- strategy was well distinguished from the C-
and S- strategies by reproductive traits, whereas C- and S- strategies are very similar to each other. Species with insect
pollination agent often correspond to C- strategy, wind agent to S- strategy, and species with self-pollination to R- strategy. 相似文献
3.
Inconsistent use of terminology plagues the study and management of biological invasions. The term “invasive” has been used
to describe inter alia (1) any introduced non-indigenous species; (2) introduced species that spread rapidly in a new region; and (3) introduced
species that have harmful environmental impacts, particularly on native species. The second definition in various forms is
more commonly used by ecologists, while the third definition is pervasive in policy papers and legislation. We tested the
relationship between the invasiveness of an introduced species and its impact on native biodiversity. We quantified a species’
invasiveness by both its rate of establishment and its rate of spread, while its impact was assigned a categorical ranking
based on the documented effects of the invader on native species populations. We found no correlations between these variables
for introduced plants, mammals, fishes, invertebrates, amphibians and reptiles, suggesting that the mechanisms of invasion
and impact are not strongly linked. Our results support the view that the term “invasive” should not be used to connote negative
environmental impact. 相似文献
4.
Post-establishment spread of invasive species is a major determinant of their impact, but the spatial pattern and temporal
rhythm of secondary spread are often poorly known or understood. Here we examine the spread of the European rockweed Fucus serratus over 1,500 km of shoreline after its initial discovery in Pictou, Nova Scotia (Canada) in 1868. Building upon earlier periodic
surveys, we document the current distribution of this invader and provide a historic analysis of the invasion, including the
integration of the recently-detected multiple introductions from Europe. The initial spread was rapid in the southern Gulf
of St. Lawrence (6.0 km year−1), likely due to both natural spread in a favorable environment and the extensive regional shipping traffic at the time which
linked Pictou to several key ports in eastern Canada and northeast USA. Later spread, especially along the Atlantic coast
of Nova Scotia, was slower (recently 0.9 km year−1), but included several major jumps (~50–500 km), undoubtedly due to human-mediated transport. Although the spatial extent
of the invasion has increased over the past 140 years, it has experienced several remarkable events: apparent local extinctions
of northern satellite populations, a major retraction (100–150 km) along the northwestern limits of its continuous range,
and stalled invasions at several points and times during its southward progression. Distributional data suggest that this
invader is excluding congeners in shallow zones and possibly kelp species in deeper zones. Genetic data from one contact zone
showed hybridization with native F. distichus but no evidence for introgression in migrating F. serratus. Hybridization and several other reproductive traits likely contribute to the competitive dominance of the invader in this
environment. 相似文献
5.
We live in a time where climate models predict future increases in environmental variability and biological invasions are
becoming increasingly frequent. A key to developing effective responses to biological invasions in increasingly variable environments
will be estimates of their rates of spatial spread and the associated uncertainty of these estimates. Using stochastic, stage-structured,
integrodifference equation models, we show analytically that invasion speeds are asymptotically normally distributed with
a variance that decreases in time. We apply our methods to a simple juvenile–adult model with stochastic variation in reproduction
and an illustrative example with published data for the perennial herb, Calathea ovandensis. These examples buttressed by additional analysis reveal that increased variability in vital rates simultaneously slow down
invasions yet generate greater uncertainty about rates of spatial spread. Moreover, while temporal autocorrelations in vital
rates inflate variability in invasion speeds, the effect of these autocorrelations on the average invasion speed can be positive
or negative depending on life history traits and how well vital rates “remember” the past. 相似文献
6.
The timing of introduction of a new species into an ecosystem can be critical in determining the invasibility (i.e. the sensitivity
to invasion) of a resident population. Here, we use an individual-based model to test how (1) the type of competition (symmetric
versus asymmetric) and (2) seed masting influence the success of invasion by producing oscillatory dynamics in resident tree
populations. We focus on a case where two species (one resident, one invader introduced at low density) do not differ in terms
of competitive abilities. By varying the time of introduction of the invader, we show that oscillations in the resident population
favour invasion, by creating “invasibility windows” during which resource is available for the invader due to transiently
depressed resident population density. We discuss this result in the context of current knowledge on forest dynamics and invasions,
emphasizing the importance of variability in population dynamics. 相似文献
7.
Species’ life histories are often classified on a continuum from “fast” to “slow”, yet there is no consistently used definition
of this continuum. For example, some researchers include body mass as one of the traits defining the continuum, others factor
it out by analysing body-mass residuals, a third group performs both of these analyses and uses the terms “fast” and “slow”
in both ways, while still others do not mention body mass at all. Our analysis of European and North American freshwater fish,
mammals, and birds (N = 2,288 species) shows the fundamental differences between life-history patterns of raw data and of body-mass residuals.
Specifically, in fish and mammals, the number of traits defining the continuum decreases if body-mass residuals are analysed.
In birds, the continuum is defined by a different set of traits if body mass is factored out. Our study also exposes important
dissimilarities among the three taxonomic groups analysed. For example, while mammals and birds with a “slow” life history
have a low fecundity, the opposite is true for fish. We conclude that our understanding of life histories will improve if
differences between patterns of raw data and of body-mass residuals are acknowledged, as well as differences among taxonomic
groups, instead of using the “fast–slow continuum” too indiscriminately for any covarying traits that appear to suit the idea. 相似文献
8.
Both community ecology and conservation biology seek further understanding of factors governing the advance of an invasive
species. We model biological invasion as an individual-based, stochastic process on a two-dimensional landscape. An ecologically
superior invader and a resident species compete for space preemptively. Our general model includes the basic contact process
and a variant of the Eden model as special cases. We employ the concept of a “roughened” front to quantify effects of discreteness
and stochasticity on invasion; we emphasize the probability distribution of the front-runner’s relative position. That is,
we analyze the location of the most advanced invader as the extreme deviation about the front’s mean position. We find that
a class of models with different assumptions about neighborhood interactions exhibits universal characteristics. That is,
key features of the invasion dynamics span a class of models, independently of locally detailed demographic rules. Our results
integrate theories of invasive spatial growth and generate novel hypotheses linking habitat or landscape size (length of the
invading front) to invasion velocity, and to the relative position of the most advanced invader. 相似文献
9.
Invasion biology suffers from a lack of the ability to predict the outcome of particular invasions because of reliance on verbal models and lack of rigorous experimental data at the appropriate scale. More progress is likely to be made by considering invasions as population-level phenomena and initially focusing on specific taxa or particular categories of invasions. To this end, we propose a simple conceptual framework to motivate studies of invasion by salmonids (salmon, trout, grayling, and whitefish) in streams that emphasizes population-level mechanisms affecting native species and promoting spread by the invader. Specifically, the only direct mechanisms by which the abundance of the native species can decline are through biotic interactions which cause decreased reproductive rates or survival at specific life stages, net emigration, debilitating or fatal diseases introduced by the invader, or a combination of these factors. Conversely, abundance of the invader must increase by local reproduction, high survival, net immigration, or a combination of these factors. Review of existing salmonid invasion literature suggests that future studies could be improved by using manipulative field experiments at a spatial and temporal scale appropriate to address population-level processes, characterizing how movement affects the establishment and spread of an invader, and including abiotic context in experimental designs. Using the example of brook trout (Salvelinus fontinalis) invasion into streams containing native Colorado River cutthroat trout (Oncorhynchus clarki pleuriticus) in the central Rocky Mountains (USA), we demonstrate how the framework can be used to design a manipulative field experiment to test for population-level mechanisms causing ecological effects and promoting invasion success. Experiments of this type will give invasion ecologists a useful example of how a taxon-specific invasion framework can improve the ability to predict ecological effects, and provide fishery biologists with the quantitative foundation necessary to better manage stream salmonid invasions. 相似文献
10.
Life history trade-offs should be detectable as negative correlations between the relevant traits (e.g. reproductive output
versus energy storage), but may be masked by variation in resource levels among individuals. One way to detect underlying
trade-offs, at least in organisms that rely on stored energy for reproduction (“capital breeders”), may be to monitor an individual's
energy stores before and after reproduction. We analysed energy stores and reproductive output in Eulamprus tympanum, a viviparous scincid lizard that stores energy for reproduction in its tail. One predicted trade-off (that between the size
and number of offspring in a litter) is consistently observed, and is detectable with minimal information. Another predicted
trade-off (that between offspring size and subsequent energy reserves) is not apparent in our data, perhaps because of constraints
imposed by correlations among other traits. Finally, trade-offs between reproductive output and subsequent energy stores are
evident in this species, but are only detectable with information on the extent of pre-reproductive as well as post-reproductive
energy stores. For “capital breeders”, non-destructive measurement of pre- and post-reproductive energy stores may greatly
enhance our ability to detect significant life history trade-offs.
Received: 10 July 1996 / Accepted: 16 January 1997 相似文献
11.
The intentional introduction of exotic species can increase the level of local biodiversity, enrich people’s material lives,
and bring significant social and economic benefits that are also the symbols of human progress. However, along with the frequent
intercourse among countries and regions, the frequency of uncontrolled crossregional migration of species is increased and
there is a lack of scientific management strategy for the intentional introduction of exotic species. Exotic species invasion,
which is behind habitat fragmentation, has become the second largest threatening factor to the maintenance of the global-scale
level of biological diversity. Exotic species invasion can destroy the structure of an ecosystem, disturb the economic life
of a society, and do harm to human health. In this paper, the authors review some of the ecological explanations for issues
such as “what causes or mechanisms have led to the successful invasion of exotic species”, including the “ideal weeds characteristics”,
“biodiversity resistance hypothesis”, “enemies release hypothesis”, “evolution of increased competitive ability hypothesis”,
“niche opportunity hypothesis”, and “novel weapon hypothesis”. The authors also analyze and evaluate the background and theoretical
basis of the hypotheses, providing explanations for some phenomena, as well as the deficiencies of these explanations. 相似文献
12.
Yingxin Huang Xueyong Zhao Hongxuan Zhang Wisdom Japhet Xiaoan Zuo Yayong Luo Gang Huang 《Journal of Plant Biology》2009,52(3):210-219
We monitored the allometric effects for greenhouse-grown Agriophyllum squarrosum plants in response to variations in population density and the availability of soil nutrients and water. Biomass allocations
were size-dependent. The plasticity of roots, stems, leaves, and reproductive effort was “true” in response to changes in
nutrient content. At a low level of soil minerals, plants allocated more resources to the development of roots and reproductive
organs than to leaves, but data for stem allocations were consistent for tradeoffs between the effects of nutrients and plant
size. The plasticities of leaf allocation and reproductive effort were “true” whereas those of root and stem allocations were
“apparent” in response to fluctuations in soil water, being a function of plant size. Decreasing soil water content was associated
with higher leaf allocation and lower reproductive effort. Except for this “apparent” plasticity of leaf allocation, none
was detected with population density on biomass allocation. Architectural traits were determinants of the latter. For roots,
the determining trait was the ratio of plant height to total biomass; for stems and reproduction, plant height; and for leaves,
the ratio of branch numbers to plant height. 相似文献
13.
Philipp Emanuel Hirsch 《Biological invasions》2009,11(3):515-521
Biological invasions are a major threat to global biodiversity. Invasive freshwater crayfish in that context are especially
prominent for their negative effects on both ecosystem integrity and native crayfish. However, some systems may have supported
a crayfish species not originally native to the system without perceivable negative consequences for the ecosystem while other
invasive crayfish species may constitute a major threat to ecosystem stability. Here I present an example how two crayfish,
the spiny-cheek and the Galician crayfish both by researchers and governmental agencies considered non-native differ in their
threats to the native ecosystem. Whereas the spiny-cheek crayfish is a recent potentially disease-transmitting and still spreading
invader with high local densities the Galician crayfish might be part of the lake’s fauna since several hundred years, appears
in lower densities and is unlikely to be a vector of disease. Therefore, regardless of the Galician crayfish’s actual date
of introduction it is thus a rather “old and integrated” invader, which is now being faced and itself potentially threatened
by the emergence of a “new and dangerous” invader: the spiny-cheek crayfish. This also exemplifies that in the face of often
insufficient scientific information about dates of species introductions care should be taken in postulating species as invasive
and dangerous without any form of risk assessment for their impact on the ecosystem. 相似文献
14.
Yōta Yokoi 《Journal of plant research》1976,89(1):1-14
To analyse the whole life of higher plants, an attempt was made to describe their growth and reproduction by mathematical
models based on the elements determining matter production and economy of the matter. A plant body was regarded as a compound
system of two parts; “productive part” and “reproductive part”. A parameter (reproductive index) was introduced to connect
these two parts, and a set of the mathematical models describing the quantitative growth of these two parts were established.
Two basic patterns of reproduction in higher plants were distinguished into “D-reproduction” and “I-reproduction”. The state of matter production of the mother plant determined an initial size of the daughter plant in theD-reproduction, while, in theI-reproduction, it did not determine the initial size of the daughter, but determined the number of propagules. The model of
each reproduction pattern was also constructed. A formula determining the initial size of a plant in a given generation was
constructed as the model of theD-reproduction. The model for theI-reproduction described the number of propagules produced in a given generation. Some aspects of the plant life, e.g. the
optimum reproductive index, the switch-over time from the vegetative to the reproductive growth phase, the seed number, types
of expansive reproduction, were theoretically analysed and discussed under these mathematical models. 相似文献
15.
Catherine Driscoll 《Biology & philosophy》2009,24(5):665-686
This paper critiques the competing “Grandmother Hypothesis” and “Embodied Capital Theory” as evolutionary explanations of
the peculiarities of human life history traits. Instead, I argue that the correct explanation for human life history probably
involves elements of both hypotheses: long male developmental periods and lives probably evolved due to group selection for
male hunting via increased female fertility, and female long lives due to the differential contribution women’s complex foraging
skills made to their children and grandchildren’s nutritional status within groups provisioned by male hunting. 相似文献
16.
Emmanuelle Sebert-Cuvillier Matthieu Simonet Valérie Simon-Goyheneche Frédéric Paccaut Olivier Goubet Guillaume Decocq 《Biological invasions》2010,12(5):1183-1206
To model the invasion of Prunus serotina invasion within a real forest landscape we built a spatially explicit, non-linear Markov chain which incorporated a stage-structured
population matrix and dispersal functions. Sensitivity analyses were subsequently conducted to identify key processes controlling
the spatial spread of the invader, testing the hypothesis that the landscape invasion patterns are driven in the most part
by disturbance patterns, local demographical processes controlling propagule pressure, habitat suitability, and long-distance
dispersal. When offspring emigration was considered as a density-dependent phenomenon, local demographic factors generated
invasion patterns at larger spatial scales through three factors: adult longevity; adult fecundity; and the intensity of self-thinning
during stand development. Three other factors acted at the landscape scale: habitat quality, which determined the proportion
of the landscape mosaic which was potentially invasible; disturbances, which determined when suitable habitats became temporarily
invasible; and the existence of long distance dispersal events, which determined how far from the existing source populations
new founder populations could be created. As a flexible “all-in-one” model, PRUNUS offers perspectives for generalization to other plant invasions, and the study of interactions between key processes at multiple
spatial scales. 相似文献
17.
18.
Competition between species is ubiquitous in nature and therefore widely studied in ecology through experiment and theory.
One of the central questions is under which conditions a (rare) invader can establish itself in a landscape dominated by a
resident species at carrying capacity. Applying the same question with the roles of the invader and resident reversed leads
to the principle that “mutual invasibility implies coexistence.” A related but different question is how fast a locally introduced
invader spreads into a landscape (with or without competing resident), provided it can invade. We explore some aspects of
these questions in a deterministic, spatially explicit model for two competing species with discrete non-overlapping generations
in a patchy periodic environment. We obtain threshold values for fragmentation levels and dispersal distances that allow for
mutual invasion and coexistence even if the non-spatial competition model predicts competitive exclusion. We obtain exact
results when dispersal is governed by a Laplace kernel. Using the average dispersal success, we develop a mathematical framework
to obtain approximate results that are independent of the exact dispersal patterns, and we show numerically that these approximations
are very accurate. 相似文献
19.
Pleuroxus denticulatus Birge, 1879 is a new invader from Western to Central Europe. Its occurrence in a Danube inundation
(Slovak region) probably corresponds with the junction of the Danube and Rhine Rivers. The species was found among ‘the hard
macrophytes’ of flowing arms and artificial ponds.
A large variability was recorded in the number of valval denticles and in postabdominal denticulation. It is evident that
part of the N. American populations is different from European populations. P. denticulatus seems to represent two sibling
species. Both are characterised by an angular distal postabdominal corner, bearing 3–4 denticles, and by valval denticles
on the postero-ventral corner.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
Zheng X Wu JG Lou XY Xu HM Shi CH 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2008,116(3):335-342
Investigations to identify quantitative trait loci (QTLs) governing cooking quality traits including amylose content, gel
consistency and gelatinization temperature (expressed by the alkali spread value) were conducted using a set of 241 RIL populations
derived from an elite hybrid cross of “Zhenshan 97” × “Minghui 63” and their reciprocal backcrosses BC1F1 and BC2F1 populations in two environments. QTLs and QTL × environment interactions were analyzed by using the genetic model with endosperm
and maternal effects and environmental interaction effects on quantitative traits of seed in cereal crops. The results suggested
that a total of seven QTLs were associated with cooking quality of rice, which were subsequently mapped to chromosomes 1,
4 and 6. Six of these QTLs were also found to have environmental interaction effects. 相似文献