ESS 002: Life on Earth

Origin and Evolution. Organization and Interaction. Background Extinctions and Mass Extinctions

Emergence

Spontaneous appearance of novel properties not predictable by studying system’s parts

Origin of Life’s Stages

1. Abiotic synthesis of small organic molecules (amino acids & nucleotide)

2. Joining of small molecules into macromolecules (proteins & nucleic acids)

3. Packaging of macromolecules with membranes maintaining an internal chemistry different from that of their surrounding

4. Self replicating molecules that made inheritance possible

Endosymbiotic theory

Eukaryotes evolved from a prokaryotic community. Multicellular eukaryotes evolved at least 1.2 billion years ago

Evolution

The process from which life has changed over time based on the random genetic changes in populations of organisms through generations by means of natural selection

Cambrian Explosion (~540 MYA)

Evolution of all major animal body plans and all the major groups

Mesozoic (~65 MYA)

flowering plants, birds, and mammals, including primates, began to dominate the landscape

Modern Humans origin

Homo sapiens ~195,000 years ago

Organization of Life

biosphere, ecosystem, population, community, organism.

population

group of individuals of a species living together and interacting regularly in an area

species

Group of populations whose members can interbreed with each other to produce fertile offspring

habitat

the place where organism lives where it finds food, shelter and mates

niche

the role of species in a community

competition

either intra or interspecific

predation

1 species feeds directly on all or part

of another one

parasitism

1 species (the parasite) feeds on another

(the host) by living on or inside it

mutualism

Both (mutually) benefit by providing

each other with food, shelter

Commensalism

1 benefits but the other is neither helped or harmed

r-strategists for reproduction

numerous offspring

low survival rate

li2le parental care

Usually: small body size

early maturity

short life spans

k-strategists for carrying capacity

few offspring

high survival rate

high parental care

Usually: large body size

late maturity

long life spans

extinction of species

permanent loss of any species from Earth

biological extinction

when ~25-95% of all species on the are wiped out in one catastrophic event

threatened species

decline numbers. still enough to survive in the short term (likely to become endangered)

endangered species

so few individual survivors (species to soon be extinct)