species

Examples of species in the following topics:

• Speciation

  • Speciation is an event in which a single species may branch to form two or more new species.
  • Many species are similar enough that hybrid offspring are possible and may often occur in nature, but for the majority of species this rule generally holds.
  • In fact, the presence in nature of hybrids between similar species suggests that they may have descended from a single interbreeding species: the speciation process may not yet be completed.
  • Given the extraordinary diversity of life on the planet, there must be mechanisms for speciation: the formation of two species from one original species.
  • Biologists think of speciation events as the splitting of one ancestral species into two descendant species.

• The Role of Species within Communities

  • Communities are shaped by foundation species and keystone species, while invasive species disrupt the natural balance of an area.
  • These include the foundation species, keystone species, and invasive species.
  • Invasive species are foreign species whose introduction can cause harm to the economy and the environment.
  • Invasive species are often better competitors than native species, resulting in population explosions.
  • The Pisaster ochraceus sea star is a keystone species.

• Exotic Species

  • Exotic species introduced into foreign ecosystems can threaten native species through competition for resources, predation, and disease.
  • For this reason, exotic species, also called invasive species, can threaten other species through competition for resources, predation, or disease.
  • Invasive species that are closely related to rare native species have the potential to hybridize with the native species.
  • Invasive species cause competition for native species.
  • Describe the impact of exotic and invasive species on native species

• The Biological Species Concept

  • According to this definition, one species is distinguished from another when, in nature, it is not possible for matings between individuals from each species to produce fertile offspring.
  • Species' appearance can be misleading in suggesting an ability or inability to mate.
  • Thus, even though hybridization may take place, the two species still remain separate.
  • Populations of species share a gene pool: a collection of all the variants of genes in the species.
  • Species that appear similar may not be able to reproduce.

• Types of Biodiversity

  • Species can be difficult to define, but most biologists still feel comfortable with the concept and are able to identify and count eukaryotic species in most contexts.
  • A species' future potential for adaptation depends on the genetic diversity held in the genomes of the individuals in populations that make up the species.
  • A genus with very different types of species will have more genetic diversity than a genus with species that look alike and have similar ecologies.
  • A recent estimate suggests that the number of identified eukaryote species, about 1.5 million species, account for less than 20 percent of the total number of eukaryote species present on the planet (8.7 million species, by one estimate) .
  • In addition, the unique characteristics of each species make it potentially valuable to humans or other species on which humans depend.

• Changing Human Behavior in Response to Biodiversity Loss

  • In the United States, the Endangered Species Act (ESA) was enacted in 1973.
  • More fundamentally, the approach to protecting individual species rather than entire ecosystems is inefficient as it focuses efforts on a few highly-visible and often charismatic species, perhaps at the expense of other species that go unprotected.
  • The Act now lists over 800 protected species.
  • Captive breeding is meant to prevent species extinction and to stabilize the population of the species so that it will not disappear.
  • Detail the benefits and limitations of different human responses to climate change and species loss, such as using preserves to conserve species

• Present-Time Extinctions

  • The last of the species was killed in 1768, which amounts to 27 years between the species' first contact with Europeans and its extinction.
  • Secondly, the number of recently-extinct species is increasing because extinct species now are being described from skeletal remains.
  • The species-area relationship is the rate at which new species are seen when the area surveyed is increased.
  • Species-area estimates have led to species extinction rate calculations of about 1000 E/MSY and higher.
  • Recent work has also called into question the applicability of the species-area relationship when estimating the loss of species.

• Species Distribution

  • Scientists gain insight into a species' biology and ecology from studying spatial distribution of individuals.
  • Patterns are often characteristic of a particular species; they depend on local environmental conditions and the species' growth characteristics (as for plants) or behavior (as for animals).
  • Uniform dispersion is observed in plant species that inhibit the growth of nearby individuals.
  • Just as lower density species might have more difficulty finding a mate, solitary species with a random distribution might have a similar difficulty when compared to social species clumped together in groups.
  • Differentiate among the ways in which species distribute themselves in space

• Biogeography and the Distribution of Species

  • The biological distribution of species is based on the movement of tectonic plates over a period of time.
  • Ecologists who study biogeography examine patterns of species distribution.
  • Other species are generalists: species which live in a wide variety of geographic areas; the raccoon, for example, is native to most of North and Central America.
  • Approximately 3/4 of living plant and mammal species are endemic species found solely in Australia .
  • Australia is home to many endemic species.

• Measuring Biodiversity

  • As of mid-2012, close to 150,000 named species had been barcoded.
  • Early studies suggest there are significant numbers of undescribed species that looked too much like sibling species to previously be recognized as different.
  • Numerous computer databases now provide information about named species and a framework for adding new species.
  • Many, perhaps most, species on the planet do not have that much time.
  • In 2011, the list contained 61,000 species, all with supporting documentation.