Biodiversity Biodiversity The variety of Earths species the

Biodiversity

Biodiversity • The variety of Earth’s species, the genes they contain, the ecosystems in which they live, & their functions in energy flow & nutrient cycling Destroying the rain forest for economic gain is like burning a Renaissance painting to cook a meal. ~ E. O. Wilson

Three Components

What affects biodiversity? • Natural Selection/Evolution • Speciation • Extinction

Evolution • Change in a species’ genetic makeup over time

Natural Selection • Individuals with certain traits are more likely to survive and reproduce under a particular set of environmental conditions than those without the traits • Begins with mutations

Adaptation Video

Resistance A group of bacteria, including genetically resistant ones, are exposed to an antibiotic Normal bacterium Resistant bacterium Most of the normal bacteria die The genetically resistant bacteria start multiplying Eventually the resistant strain replaces the strain affected by the antibiotic

Limits to Natural Selection • When a change in environmental conditions occurs, a gene/mutation must already occur in the population • Reproductive capacity • Fast reproduction = quicker adaptation • Slow reproduction = slow adaptation

r Selected • Unstable environments • Small body size • High fecundity • Early maturity • Short generation time • Less parental care

K selected • Stable environments • Large body size • Long life expectancy • Later maturation • Few offspring • More parental care

Reproductive Strategies R- strategists K-strategists Mature rapidly Mature slowly Short lived Long lived Tend to be prey Tend to be both predator and prey Have many offspring and overproduce Have few offspring Low parental care High parental care Generally not endangered Most endangered species are K-strategists Wide fluctuation in population density (booms and busts) Population stabilizes near carrying capacity Population size limited by densityindependent factors (climate, weather, natural disasters, requirements for growth) Density-dependent limiting factors to population growth stem from intraspecific competition and include predation, parasitism, and migration Tend to be small Then to be larger Type III survivorship curve Type I or II survivorship curve Examples: most insects, annual plants, bacteria, rodents Examples: humans, elephants, cacti and sharks

Survivorship curves What do these graphs tell about survival & strategy of a species? Generalized life strategies Survival per thousand 1000 Human (type I) I. High death rate in post-reproductive years Hydra (type II) 100 II. Constant mortality rate throughout life span Oyster (type III) 10 1 0 25 50 75 Percent of maximum life span 100 III. Very high early mortality but the few survivors then live long (stay reproductive)

Survivorship Curves Type Descriptions I Late Loss Reproduction occurs fairly early in life. Most deaths occur at the limit of biological life span. Low mortality art birth. High probability of surviving to advanced age. Advances in prenatal care, nutrition, disease prevention and cures mean longer life spans for humans. Examples: humans, annual plants, sheep and elephants. II Constant Loss Individuals in all age categories have fairly uniform death rates. Predations affecting all age categories is primary means of death. Typical of organisms that reach adult stages quickly. Examples: rodents, perennial plants and songbirds. III Early Loss Typical of species that have great numbers of offspring and reproduce for most of their lifetime. Death is prevalent for younger members of the species (environmental loss and predation) and declines with age. Examples: sea turtles, trees, internal parasites, fish and oysters.

Speciation One species splits into two of more different species Two mechanisms: 1. Geographic Isolation 2. Reproductive Isolation

Geographic Isolation Occurs when a population become physically isolated from one another for a long period of time mountains rivers landslides

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

Speciation in Action California Salamanders

Extinction Two Types 1. Biological • The process in which an entire species ceases to exist • Local • A population of a species becomes extinct over a large region but not globally

Passenger Pigeon • 3 -5 billion – first European settlers • Last died 1914 • Cincinnati zoo - Martha • Caused by • Habitat destruction • Over hunting

Endemic Species only found in one area • Highly vulnerable to extinction

Types of Biological Extinction • Background extinction • Species disappearing at a slow rate • Mass extinction • Significantly high rate of extinction • 25 -95% of global species gone • Largest Permian – 96% of species died • Promotes evolution

Endangered Species So few individuals that the species could become extinct • Reasons • Habitat loss/fragmentation • Invasive species • Pollution • Population growth • Climate change • Overconsumption

Keystone Species • A species that plays a critical role in ecosystem structure & whose impact on the community is greater than expected based on abundance • Removal greatly affects the food web

Keystone Species Sea Otters

Keystone Species Grey Wolves

Invasive Species • A non native (introduced) species that adversely affects a habitat they invade ecologically and/or economically

Invasive Species Where do they come from? • Horticulture • Conservation • Accidental

Invasive Species Characteristics • Tolerate a variety of habitat conditions • Reproduce rapidly • Short generation time • Great competitors • generalist • Lack of predators • Genetic variability

Indicator Species that provide early warning signs of damage to an ecosystem Examples: Lichens (air quality) Stoneflies (aquatic – DO) Pika – (climate change)

Levels of Diversity • Ecosystem Diversity • Different habitats, niches, interactions • Species Diversity • Different types of organisms • Genetic Diversity • Different genes & combinations within a population

Measuring Species Diversity Two components: 1. Species richness • Number of unique species 2. Species evenness • Number of individuals of each species in an area

Monoculture • Opposite of biodiversity • Growing only one species of organism • Problem? • disease

Which do you think is more diverse? A B

Which do you think is more diverse? A B

Which do you think is more diverse? A B

Leaf Litter • Insects are critical to the health of the environment. • Decomposition • Recycling nutrients • Lower invertebrates result in less stability and health

Laboratory Set Up • Leaf litter from bags into funnels • Funnel was placed over beaker with ~100 m. L ethanol • Removed preserved insects next day • Microscope for observation • Classified and tallied number of insects