Ecosystem Services. Biodiversity Climate Mitigation of floods and droughts Services provided by soil Pollination Pest control Seed dispersal Aesthetic beauty. BIOSPHERE 2. Biosphere 2. 3.15-acre artificial closed ecological system outside Tucson
--John Avise, “The Real Message From Biosphere 2”
It’s widely agreed that there is a biodiversity crisis. Legislation and treaties are enacted to help stop it. But what is biodiversity, and why do we value it? Should we value it?
Certainly the best-known impact of the ESA is the establishment of broad prohibitions against any take of endangered and threatened animal species. However, another major intention of the act is to integrate federal and international legislation on endangered species, including the national-level implementation of CITES (Convention on International Trade in Endangered Species of Wild Flora and Fauna, 1973). Within this structure, the ESA establishes guidelines to define categories and listing protocols for endangered and threatened species (Sec. 4). In addition, the act defines the concept of "critical habitat". Federal agencies are required to (a) actively promote the conservation of listed species; and (b) avoid any actions that would have negative effects on listed species and their critical habitat. Finally, the ESA provides matching federal funds for some state actions in support of the act and authorizes the acquisition of land for plants and animals listed under CITES.”
(Go to ESA pdf…)
How does a species get listed as an endangered or threatened species?
Taxonomy: species (sapiens), genus (Homo), family (hominid), order (primates), class (mammal), phylum (chordate), kingdom (animal)
Makes species a conventional distinction
Males, females, juveniles may differ markedly in appearance/behavior
The notion of potentially interbreeding is slippery
How do we count lineages?
Both 2 and 3 are “historical” definitions. No intrinsic property makes you or anything a member of a species.
1.5 million species have been catalogued. It is thought that there are currently 10 and 100 million that exist on Earth.
The biological species concept defines a species as members of populations that actually or potentially interbreed in nature, not according to similarity of appearance. Although appearance is helpful in identifying species, it does not define species.
Appearance isn’t everything
Organisms may appear to be alike and be different species. For example, Western meadowlarks (Sturnella neglecta) and Eastern meadowlarks (Sturnella magna) look almost identical to one another, yet do not interbreed with each other—thus, they are separate species according to this definition.
The Western meadowlark and the Eastern meadowlark appear to be identical, and their ranges overlap, but their distinct songs prevent interbreeding.t interbreeding.
Organisms may look different and yet be the same species. For example, look at these ants. You might think that they are distantly related species. In fact, they are sisters—two ants of the species Pheidole barbata, fulfilling different roles in the same colony.
Many characteristics can vary within a single species. For example, the plant hydrangea may have pink “flowers”—they’re actually modified leaves—or blue “flowers.” But that doesn’t mean that we should classify the two forms as different species. In fact, you could cause a blue-“flowered” plant to become a pink-“flowered” plant just by changing the pH of the soil and the amount of aluminum taken up by the plant.
In The Diversity of Life, E.O. Wilson uses conservative values to scale species loss to area reduction and the rate of tropical deforestation. He arrives at about 0.25% of tropical forest species extinguished or committed to early extinction annually (Wilson 1999, p. 280). Since most species likely occur in tropical forests, these ecosystems are a good proxy: even if no extinction occurred elsewhere, the planetary rate would still be 1,000 times prehuman levels. (What do we mean by ﾒcommitted to early extinctionﾓ? Studies from forests show that when forests are reduced to even large fragments, then 10ﾐ50% of the species go extinct within 100 years (see footnote above). The area-dependent decline in mammal species in national parks also accords with the picture of committed extinction by a real reduction alone (Newmark 1996) .