Conservation Biology

As the human population has grown, and our use of resources has increased, we have destroyed the habitat of many species. A biodiversity crisis has developed. The Red List of Threatened Species, compiled by the World Conservation Union, lists 16,913 species as threatened with extinction. Conservation biology—the scientific study of phenomena that affect the maintenance,…

Energy Production: Primary production, Gross primary production, Net primary production

The term ecosystem was first used by Tansley (1935) to refer to all the components of an ecological system, biotic and abiotic, that influence the flow of energy and elements. The ecosystem concept integrates ecology with other disciplines such as geochemistry, hydrology, and atmospheric science. Primary production is the chemical energy generated by autotrophs during…

Ecology: Population Distribution and Abundance

Distribution: Geographic area where individuals of a species occur. Abundance: Number of individuals in a given area. Ecologists try to understand what factors determine the distribution and abundance of species. Populations are dynamic—distribution and abundance can change over time and space. ***Understanding the factors that influence these dynamics helps us manage populations for harvest or…

Life History: Diversity, Reproduction, K vs. R species, Tradeoffs

An organism’s life history is a record of events relating to its growth, development, reproduction, and survival. Life history characteristics include: Age and size at sexual maturity. Amount and timing of reproduction. Survival and mortality rates. Life History Diversity Individuals within a species show variation in life history traits due to genetic variation or environmental…

Coping with Environmental Variation: Temperature and Water

The physical environment influences an organism’s ecological success in two ways: Availability of energy and resources—impacts growth and reproduction. Extreme conditions can exceed tolerance limits and impact survival. Energy supply can influence an organism’s ability to tolerate environmental extremes. The actual geographic distribution of a species is often lower than potential distribution due to other…

Forms of Sexual Contraception & Types of Abortion

Contraception Combination Pill: Birth control pills that contain a combination of estrogen and progestin (progesterone) (21 days on, 7 placebo) The pill works by preventing ovulation; keeps estrogen high inhibits LSH and no ovulation; high progesterone inhibits LH . Keep endometrium lining thick and prevents sperms from effectively travelling Failure Rate: percentage of women who…

Diphtheria (Corynebacterium diphtheriae): History, Symptoms, Causes, Treatment

Corynebacteria are Gram-positive, aerobic, nonmotile, rod-shaped bacteria related to the Actinomycetes. They do not form spores or branch as do the actinomycetes, but they have the characteristic of forming irregular shaped, club-shaped or V-shaped arrangements in normal growth. They undergo snapping movements just after cell division which brings them into characteristic arrangements resembling Chinese letters.…