From wind-swept seeds to efficient flight mechanism, all animals and plants have evolved a variety of dispersal abilities and have an important role in understanding species survival and evolution. Dispersal is largely driven by needs for resource acquisition particularly to seek suitable breeding habitats. Individuals dispersing between populations aid in gene spread and as such dispersal is subject to natural selection. Three main evolutionary drivers are thought to result in dispersal - habitat instability, intraspecific competition and inbreeding (Johnson and Gaines 1990). But by entering unknown areas there are potential costs, from exposure to predation risks, to unknown resource availability and possible intraspecific competition (Koenig, et al. 1996). An organism’s ability to disperse is key to understanding how a species can spread to different areas of its fundamental niche (Kokko and López-Sepulcre 2006). But how does an organism do this? Evolutionary ecologists are aware that not only intrinsic factors constrain how organisms use their habitat, but the environment itself have implications for a species ability to colonise new areas (Holt 2003). Predicting how species will respond to environmental change such as their ability to track optimal habitats and adapt to changing conditions, depends on understanding these mechanisms will be important.
The distance that an organism travels can tell us something about their preferred habitat, how they reproduce as well as being a primary determinant of their likelihood to survive. Dispersal between populations influences the likelihood of colonisation and extinction. If extinction occurs in one habitat patch populations may be rescued by individuals from a nearby population. A ...
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... authors had evidence the disperser was market near its natal site and reported movement that is defined as movement out of an area larger than its home range excluding migration. Numerical values were estimated from figures including small figures with log scales. Distances were collected only when reprted as straight line distance between start and end point. Converting distances provided as number of home ranges into kilometres assuming mean size measured in the study. The potential for sampling bias is possible due to sample size varying from 1 to 3000 between studies. Due to the decreased likelihood of detecting individuals at the edge of study, studies using small study area and presenting distance-density distribution were excluded. However statement of adequacy of site size was accepted if survey of surrounding area did not truncate distribution of distance.
Invasive species as a whole have become a nuisance to many habitats and ecosystems around the world. What defines an invasive species is the following. It must be a species that is foreign to the habitat it resides in, have no natural predators which allow it to reproduce in such a rapid manner, and out compete native animals of food and shelter (Rosenthal 2011). These characteristics are what create such high populations of these invasive species in various habitats around the globe.
Rapidly evolving throughout the late Pleistocene to the early to mid Holocene, hunter-gatherer-fisher societies hunted megafauna creatures in a systematic and ethical way. When one species migrates to a different ecosystem, that species is not usually recognized as a threat to other species. Survival, during the late Pleistocene and Holocene era, was one of the most important aspects to life. Any organism, regardless of size, living within their environment had to stay alive and reproduce. During these two eras, it seems...
Soule, Michael E et al. “Ecological Effectiveness: Conservation Goals for Interactive Species.” Conservation Biology 17.5 (2003) : 1238-1250.
Natural selection is associated with the phrase “survival of the fittest.” This basically means that the fittest individuals can not only survive, but are also able to leave the most offspring. The selection of phenotypes affects the genotypes. For example, if tall pea plants are favored in the environment, then the tall pea plants would leave more offspring behind, meaning that the offspring will carry tall alleles. Phenotypes that are successful have the best adaptations (characteristics that help an individual to survive and reproduce) to their environment. These adaptation arise from the interactions with living and nonliving aspects of the environment. Some nonliving aspects of the environment are climate, water availability, and concentration of mineral sin the
Biodiversity is influenced by landscape fragmentation at various scales of space and time. The extinction of ecosystem types and component species may cause an increased patchiness of the landscape, resulting in lower population sizes and decreased connectivity. As a result, inhabitants may experience decreased dispersal abilities and lowered gene flows between populations.
Long-term survival of a species depends on its ability to adapt to changing environmental conditions (Murphy, 1994). Genetic diversity within a species, which has taken 3.5 billion years to evolve, makes adaptations to these changing environments possible. Unfortunately, the rate of extinction of genetically diverse organisms is rapidly increasing, thus reducing this needed biodiversity, largely due to the human impacts of development and expansion. What was an average of one extinction per year before is now one extinction per hour and extinct species numbers are expected to reach approximately one million by the year 2000 (WWW site, Bio 65). As a result governmental and societal action must be taken immediately!
Mills, Scott L., Daniel F. Doak, and Michael E. Soule. "The Keystone-species Concept in Ecology and Conservation." BioScience 43.4 (1993): 219-25. Apr. 1993. Web. 30 Oct. 2011.
A different scenario takes place when an alien species is transported to a new area. Although direct competition with similar species is still a problem, the new kid in the block may have no natural pests and diseases. Thus, large stands of monocultures can occur. It is generally accepted that one plant species will support 10 species of animals. If one species takes over 99% of a given habitat dozens if not hundreds of species are lost from that area and some populations are stressed enough that extinction is possible.
One of the most important results concluded from this article is the fact that hybrid movements are becoming a widespread concern that deserves more attention. Since 1985, 28 hybrid zones have been analyzed and found unstable, and at the time of the article, another 16 zones were displaying molecular markers that could be a result of a potential movement. With numbers like this, Buggs states that these areas deserve more ecological and evolutionary studies performed on them. The paper also shows how multiple factors (both natural and human-induced) usually influence a zone’s movement, yet a “disentanglement” of the influence of each individual’s impact remains under-studied. Although this paper asked more questions than answered, it highlighted the importance that we further examine these zone movements to truly understand what is going on.
Zacherl, Danielle. “Biology 171 Evolution and Biodiversity.” National Association of Research in Science Teaching 2007 Annual Meeting, New Orleans LA. (2007):n. page. Print.
On the first level, when foreign, but previously non-invasive species is first introduced to a new area, the new species may play a role in a community that was previously unfulfilled; it may fill a vacant niche in the ecosystem. Originally this new species may be seen as a useful contributor to its new surroundings because it has only (temporarily) increased biodiversity in the area (Meinesz, 2003).
Darwin’s observations from the islands made him want to come up with some explanation to why this occurred. He began to do research of each the species that had lived on these islands and observe all of the characteristics that had. He noticed that the islands h...
Extinction, although not as pleasant a concept as the idea of adapting to ones surroundings, plays just as large a role in natural selection as anything else. As one adaptation of a species proves beneficial, and as that variation begins to propagate, the original, less advantageous variant will die off. It is the unchanged species that are in immediate conflict with the species undergoing the natural adaptation that stand to suffer...
Humans are very quickly dominating the globe. Today, the human population is around 7 billion people. Humans are populating at a rate of almost 220,000 per day! Humans are rapidly heading towards Earth’s carrying capacity.
*The speed of migration is different for different species, depending on when they migrate. *A new study has found interesting differences in the migration speeds of early and late migrants between Europe and Africa. *In general, flight velocity of birds ranges from 20 to 50 miles per hour. *For sustained flight, larger birds typically fly faster than smaller birds. * A common flying speed of ducks and geese is between 40 and 50 miles per hour, but among the smaller birds it is much less. *Herons, hawks, Horned Larks, ravens, and shrikes, timed with an automobile speedometer have been found to fly 22 to 28 miles per hour, whereas some of the flycatchers fly at only 10 to 17 miles per hour. *Even such fast-flying birds as the Mourning Dove