Biodiversity

Biodiversity Biological Diversity or Biodiversity, is the variety of the earth’s species, the genes they contain, the ecosystems in which they live, and the ecosystems processes such as energy flow and nutrient cycling.

Biodiversity Biodiversity increases with speciation decreases with extinction Give-and-take between speciation and extinction  changes in biodiversity

Why Biodiversity is important? It supplies us with food, wood, energy, medicines,… It preserves the air and water quality and maintains the fertility of soils. It helps us to dispose of wastes and to control populations of pests

In carrying out these free ecological services, which are also part of the earth’s natural capital, biodiversity helps to sustain life on the Earth.

Biological Evolution by Natural SELECTION

Idea Early Greek philosophers Wallace and Darwin (1858) independently proposed the concept of natural selection as a mechanism for biological evolution’ But Darwin gathered evidence and publish it in 1859 in his book, On the Origin of Species by Means of Natural Selection

Charles Darwin 1809-1882 British naturalist Proposed the idea of evolution by natural selection Collected clear evidence to support his ideas

Darwin’s Observations Most species produce more offspring than can be supported by the environment Environmental resources are limited Most populations are stable in size Individuals vary greatly in their characteristics (phenotypes) Variation is heritable (genotypes)

Darwin’s finches 13 species of finches in the Galápagos Islands Was puzzling since only 1 species of this bird on the mainland of South America, 600 miles to the east, where they had all presumably originated Darwin noted that the plants and animals of South America were very distinct from those of Europe. Organisms from temperate regions of South America were more similar to those from the tropics of South America than to those from temperate regions of Europe. Further, South American fossils more closely resembled modern species from that continent than those from Europe.

Darwin’s finches Differences in beaks associated with eating different foods adaptations to the foods available on their home islands Darwin concluded that when the original South American finches reached the islands, they adapted to available food in different environments

What did Darwin say? Organisms reproduce more than the environment can support some offspring survive some offspring don’t survive competition for food for mates for nesting spots to get away from predators

Survival of the fittest Who is the fittest? traits fit the environment the environment can change, so who is fit can change Peppered moth

According to this theory, life has evolved into six major groups of species, called Kingdoms. Tree of life (development of life)

At any given moment (e.g. the ‘present’), all we see is current diversity… all extinct forms are gone (99.9%) Time 

Lamarck Lamarck’s theory stated that organisms evolve over time due to the environmental factors that act upon that organism If they began to use an organ more than they had in the past, it would increase in its lifetime. Meanwhile organs that organisms stopped using would shrink.

Fossil Record: The world’s cumulative body of fossils found. Fossils: Mineralized or petrified replicas of skeletons, bones,… or impressions found in rocks Strongest evidence for evolution

Main cause of evolutionary change: Mutation: random changes in the structure or number DNA molecules in a cell that can be inherited by offspring. Mutations can occur in any cell, but only those taking place in reproductive cells are passed on to offspring. New genetic traits that give better chances for survival (now or in the future)

Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with theses traits (natural selection)

Adaptation An adaptation or adaptive trait, is any heritable trait that enables and individual organism to survive through natural selection and to reproduce more than other individuals under prevailing environmental conditions

For natural selection to occur,… The trait must be heritable. The trait must lead to differential reproduction, which enables individuals with the trait to leave more offspring than other members of the population.

Genetic Resistance Genetic resistance is the ability of one or more organisms in a population to tolerate a chemical design to kill it. (Ex. Bacteria)

Natural Selection acts in individuals, but evolution occurs in populations

When environmental conditions change: A population of a species faces 3 possible futures: Adapt Migrate Become extinct

Humans Page 83

How long does it takes? Populations of genetically diverse species that reproduce quickly often adapt to a change in short time. Species that cannot reproduce large numbers of offspring rapidly, take long time to adapt.

3 Common myths Survival of the fittest means survival of the strongest. Organisms develop certain traits because they need or want them. Evolution by natural selection involves some grand plan of nature in which species become more perfectly adapted.

Speciation Tectonic plate movements, volcanic eruptions, earthquakes, and climate change have shifted wildlife habitats, wiped out large number of species, and created opportunities for the evolution of new species.

Speciation One species can evolve into two or more species 2 step process Geographical isolation Reproductive isolation When a group becomes geographically isolated over time it will become reproductively isolated = new species formed. 31

Ammospermophilus spp Geographic isolation When a population becomes divided by a natural barrier. Mountains, river, body of water, landslides Groups can’t interbreed or intermix Become adapted to a different environment Harris’s antelope squirrel inhabits the canyon’s south rim (L). Just a few miles away on the north rim (R) lives the closely related white-tailed antelope squirrel 32

Reproductive Isolation Differences in isolated groups become so great, they can no longer interbreed Physical changes Behavioral changes Biochemical changes 33

How long does it takes the speciation? For some rapidly reproducing organisms, this may occur within hundreds of years. For most species, it takes from tens of thousands to millions of years.

Extinction Extinction of a species occurs when it ceases to exist; may follow environmental change - if the species does not evolve Evolution and extinction are affected by: large scale movements of continents gradual climate changes due to continental drift or orbit changes rapid climate changes due to catastrophic events

Extinction: Lights Out Extinction occurs when the population cannot adapt to changing environmental conditions. The golden toad of Costa Rica’s Monteverde cloud forest has become extinct because of changes in climate. Figure 4-11

Extinction Background extinction - species disappear at a low rate as local conditions change Mass extinction - catastrophic, wide-spread events --> abrupt increase in extinction rate Five mass extinctions in past 500 million years

How many mass extintions? Some biologists argue that a mass extintions should be distinguished by a low speciation rate as well as by a high rate of extintion. Under this: only 3 mass extintions.

A mass extintion provides an opportunity for the evolution of new species that can fill unoccupied ecological roles or newly created ones.

Species Diversity: Richness vs. Evenness Species Richness: measurement of the number of species in a given area Species Evenness: measurement of how evenly distributed organisms are among species Community A Community B species 1 25 1 species 2 0 1 species 3 25 1 species 4 25 1 species 5 25 96

Species richness appears to increase the productivity and stability or sustainability of an ecosystem. While there may be some exceptions to this, most ecologists now accept this as a useful hypothesis

the species’ occupation and its Niche is the species’ occupation and its Habitat location of species (its address)

Niche A species’ functional role in its ecosystem; includes anything affecting species survival and reproduction Range of tolerance for various physical and chemical conditions Types of resources used Interactions with living and nonliving components of ecosystems Role played in flow of energy and matter cycling

Scientists use the niches of species to classify them broadly as: Generalist species Specialists species

Types of Species Generalist large niches Live in many places Eat a variety of food tolerate wide range of environmental variations do better during changing environmental conditions Such as flies, cockroaches, mice, rats, humans,…

Types of Species Specialist narrow niches May be able to live in only one type of habitat Use one or a few types of food Tolerate a narrow range of climatic and other environmental conditions more likely to become endangered do better under consistent environmental conditions Such as tiger salamanders, China´s giant panda

Specialist species Generalist species with a narrow niche Fig. 4-7, p. 91 Specialist species with a narrow niche Generalist species with a broad niche Niche separation Number of individuals Figure 4.7 Overlap of the niches of two different species: a specialist and a generalist. In the overlap area, the two species compete for one or more of the same resources. As a result, each species can occupy only a part of its fundamental niche; the part it occupies is its realized niche. Generalist species such as a raccoon have a broad niche (right), and specialist species such as the giant panda have a narrow niche (left). Niche breadth Region of niche overlap Resource use Fig. 4-7, p. 91

Generalist Species Page 92

Any given species may play one or more of five important roles- native, nonnative, indicator, keystone, or fundation roles – in a particular ecosystem.

Types of Species Native species normally live and thrive in a particular ecosystem Nonnative species are introduced - can be called exotic or alien Indicator species serve as early warnings of danger to ecosystem- birds & amphibians Keystone species are considered of most importance in maintaining their ecosystem Foundation species help to create habitats and ecosystems

Nonnative Species Nonnative plant species are invading the nation's parks at an alarming rate, displacing native vegetation and threatening the wildlife that depend on them At some, such as Sleeping Bear Dunes National Lakeshore in Michigan, as much as 23 percent of the ground is covered with alien species, and the rate of expansion is increasing dramatically.

Indicator Species a species whose status provides information on the overall condition of the ecosystem and of other species in that ecosystem reflect the quality and changes in environmental conditions as well as aspects of community composition

Keystone Species A keystone is the stone at the top of an arch that supports the other stones and keeps the whole arch from falling a species on which the persistence of a large number of other species in the ecosystem depends. If a keystone species is removed from a system the species it supported will also disappear other dependent species will also disappear Examples top carnivores that keep prey in check large herbivores that shape the habitat in which other species live important plants that support particular insect species that are prey for birds bats that disperse the seeds of plants