Evolution & Society Lecture Slides Midterm 2


Biodiversity origins

Biodiversity comes from speciation


the process by which one species splits into two or more species

how does speciation occur

Tends to happen through populations separating and evolving separately

necessary elements to speciation

Isolation, time, and adaptation

What prevents speciation from occurring


When are populations different species

When they can no longer reproduce or if offspring produced are infertile or have dwarfism

Adaptive radiation

one species evolves into many species in a short time period, occurred with finches on Galapagos islands because of no competitors and open-niche

Biodiversity trajectory

Generally there has been an increase of biodiversity on planet

single cellular organisms

evolve to be multi-cellular

major extinction events

5 major extinction events over the past 500 Million years

Number of species predicted in 1980's

Less than 1 million macroscopic species

Experiments by Terry Erwin

counted insects in the amazon by spewing pesticides and found each insect to be its own species

current insect estimated species

Up to 5 million species of insects

Biomass of microscopic species

more microscopic organisms in/on me than humans in world, bacteria and viruses have greatest biomass

divisions of biodiversity

most is bacteria, small amount is archaeans, and everything else is very small sliver

Biomass of prokaryotes

More than all of eukaryotes combined

bacteria create how much oxygen

1/4 of Earth's oxygen

Plants origin of photosynthesis

Borrowed photosynthesis from bacteria

Digestive Bactria

helps us digest cellulose in plants and people with Crohns and IBS don't have enough bacteria, 15-20% of calories from digestion come from bacteria and helps us get vitamins B & K

Bacteria in medicane

Help create antibodies, vitamins, and chemicals and probiotic treatments

Bacteria importance

critical to ecosystems and humanity

Gut bacteria in different geographic regions

Bacteria in Westerners are able to digest toxins in the food we eat; drugs, stress, and antibiotics affect gut bacteria, C-section v natural affects bacteria

Another name for single-celled eukaryotes


Protists oxygen production

Produce 25% of oxygen

Example of protist


Energy principles

energy is key feature to life and each organisms has the ability to take in and process energy

origin of all energy

primary producers (Plants, algae, bacteria)

Energy Consumption

Consumers can only gather 10% of the energy from plants from the organisms they consume

lost energy


Biomass of species in an ecosystem

Farther away from plants in ecosystem, smaller the biomass of species and more sparse

ideal diet of humans

Would be better if we were vegan for tragedy of the commons

energy per pound

Animals have more energy per pound, but there are more plants than animals, causing a majority of energy to be found in plants

most energy stored in humans


Plant production of oxygen

50% of total

Importance of plants

cannot overstate, increase amount of fixed nitrogen, hold water in soil, creates and improves soil, hold soils and reduces erosion, provide suitable micro-climates for trillions of organisms, primary or secondary food source for almost all forms of animal

most important plant for human consumption


6 plants that make up 56% of human caloric intake

rice, wheat, maize, potatoes, manioc, and sweet potatoes

8 plants that make up additional 14% of human caloric intake

Bananas, beans, soybeans, sorghum, barley, coconuts, sugar cane, and sugar beets

Recent crisis of American agriculture

Dust Bowl

Dust Bowl problems caused by

Farmers produced more crops, drought, removal of native grasses and plants that held soil in place

Modification of plants

Plants have been modified through human artificial selection, teosinte --> maize (corn)

Original use of cannabis

stems very strong and flexible and could be used as rope

artificial selection of cannabis

Selected for more THC

Plant material holds what materials

C, N, & P ; cellulose and lignin make this material very difficult to break down


quickly breaks down lignin and cellulose and helps to keep the forrest maintained


the reproductive structure of the fungus

Fungi in relations with plants

enter symbiotic relationship with plants and help to expand their root structure

Simple end of animal diversity

sponges, jellyfish, and corals


living thing on outside of rock, secrete a rock-like substance to live in, these substances build up a large structure called coral reef


coral-like, build up and maintain reefs


much larger, motile coral, are increasing in population and could destroy ecosystem

coral death

when corals die, they "bleach" and turn white, the cost fo widespread could equal trillions of dollars

Things that cause coral bleaching

Run-off from land including sewage, fertilizers, toxins, sediment, changes in pH, increasing water temp

ways to save coral

Coral can be physically transplanted to save population


numerous, very small, motile filter feeders in damp and fresh water environments, part of the annelids

segmented worms

earthworms and leaches, very large biomass, and key to processing soil and producing fertile ground for plant growth, also known as the annelids group


can provide anesthetic and reduce bruising, part of the annelids


very diverse group with over 100,000 species, not segmented and either have hard shells over have lost this feature through evolution, secrete their own shell or steal it, are soft bodied underneath shells

examples of mollusks

Scallops, clams, snails, slugs, nudibranchs, squid, octopi, and nautili


can change color and texture, can learn how to open a lid and remember lessons learned, are color blind but their skin has photo receptors


most successful group of animals and very diverse with 4 groups within: Myriapoda, Chelicerata, Crustaceans, and Insects; barnacles are also in this group even tho they have a shell


the variety of life in the world or in a particular habitat or ecosystem.


centipedes and millipedes (14,000 species)


a sub phylum of arthropods; includes Horseshoe crabs, spiders, scorpions, mites, ticks, vats majority are terrestrial but some are aquatic; typically have 4 pairs (8) legs

Mites and Ticks

echo parasitism forms on humans, latch onto host and feed off them, 40% of people have facial mites, mites are within the tick group evolutionarily, usually no bad effects on humans but some mites help calibrate human immune system

jumping spiders

mobile and decorative


A member of a major arthropod group, usually create webs to catch prey, webs are stronger than steel by weight, can use webs to travel far distances, sit & wait predators


sub phylum of arthropods that includes lobsters, shrimp, crayfish, crabs, isopods (rally pollies), copepods, and barnacles; dominant arthropods in aquatic environments, but some (land crabs and rolls pollies) are terrestrial, made up of multiple body segm

rolly pollies

some live on ocean floor, within fish's mouth, or as large as small dog in Australia


Most successful macroscopic animals in terrestrial environments, species number and biomass are very large

Insect diets

Most eat plants, which is a crucial place in terrestrial food webs, majority are vegetarian, and are plant specialists that only eat a couple species of plants


Feeding on plants or plant material. Used especially of insects and helps energy gained by plants to be Released to the ecosystem as a whole

Rice weevils

Numerous and important in agriculture

Reasons why insects are successful

Flight and metamorphosis


change of form that helps differentiate resources and food which reduces competition

Power of flight helps other groups

Bats, birds, and flying reptiles in age of Dinos

Wings on insects

Typically have two sets of wings, fly's one pair of wings in front and back pair helps control flight, beetles have back pair of wings and front pair serves as hard coverings


exemplify the success of insects and have over a million species, "God must love Beetles" -JBS Haldane

Social insects

ants, bees, wasps, degree of sociability varies from small groups to huge colonies

Ant species

Over 20,000 ant species and biomass makes up (10-20%) of terrestrial animal biomass, very social and can go to war, separated into castes, take slaves, and use chemicals for communication, 1 Million Ants to every one human


animals with backbones

Features that have allowed vertebrates to proliferate

Jaws, Large Central Nervous System, Internal Skeleton, amniotic egg, homeothermic endotherms


evolved early on for feeding efficiency and still have have similar jaws to origins

Large Central Nervous System

Brain grew larger in regard to rest of CNS

Internal Skeleton

Allows for great size

Amniotic Egg

reptile egg that allows for drought tolerance

Advantages and Drawbacks of homeothermic endotherms

can move rapidly in cold temperatures, but we need more food to survive


vertebrates that live on land, scales cover body, lay eggs, cold blooded, ancestors of mammals and birds, could also put Dinos and birds


most successful terrestrial Vertebrates with very large biomass due partially to endothermic homeothermy and flight

3 groups of mammals

monotremes, marsupials, placentals


greatest biomass and diversity of vertebrates


360 species, herrings, shad, sardine, anchovy, live in high shoals or groups, density make them ideal for netting and catching by humans, millions of tons per year are caught but this is not sustainable


vertebrates that live in water and on land, smooth skin covers body, lay eggs, cold blooded, but are very affected by pollution, pesticides, and disease


mammals that lay eggs, platypus


Mammals whose immature offspring complete their development in an external pouch, koalas and kangaroos

placental mammals

Mammals that nourish their unborn offspring through a placenta (cord) inside the female mammal, largest group of mammals = rodents, second largest group of mammals = bats

Current Vertebrate Diversity

Fish = 1/2 of species, birds have 2x as many species as mammals


evolutionary lineage split off from apes 5 million years ago, modern humans appeared recently between 1/2 to 1/4 Million years ago

Evolutionary changes to humans

upright posture, very large brain size, social behavior, and pair bonding

Humans population size

8 Billion humans are most numerous large animal, bison were second place at 50 Million

6th extinction

Rate of extinction is rapidly increasing in most forms of life due to exponential growth of human population

Why are more species dying

Biomass of humans has rapidly risen and we need more resources

Causes of loss of biodiversity

industrial revolution, agricultural revolution, medical revolution, chemical revolution, genetic revolution; all of these help humans survive and reproduce

Species extinction

Habitat destruction is leading cause of species extinction and invasive species is second largest cause

species that have gone extinct

stellar seacow, Ard wolf in Australia, and passenger pigeon in America

Black Rhinos case study

Making poaching illegal isn't enough because the demand is still there and it is worth it for people to get paid by killing Rhinos

Value of Biodiversity

good aesthetics, 56% of calories come from 6 species and makes us vulnerable if one of those went extinct, new cures for diseases could be found in new plants Great Lakes fishing and big game hunting can stimulate economy when money goes to groups it affe


are eliminated first, but they are natural cleaners of polluted waters and create more oxygen

Keystone species

A species that influences the survival of many other species in an ecosystem, i.e. kelp

engineer species

species that is very important to whole ecosystem despite small biomass i.e. otters prevent overwhelming population of urchins

invasive species

plants and animals that have migrated to places where they are not native, usually do not survive, but some destroy native populations i.e. asian Lionfish, purple loosestrife, and bighead carp

Hawaiian Islands

Have seen a large biodiversity loss do to a loss of natural habitats due to human expansion

Climate change

Long term economics demands we preserve wetlands, coral reefs, and kelp Forrests to avoid tragedy of commons

Hope for Conservation

We have saved species in the past, just have to make it a priority