Div I Exam #1

Covers biodiversity, history of life on earth, taxonomy and systematics, and conservation

Biodiversity

variation at all levels of biological organization

Taxonomy

the science of naming, describing, and classifying living things; one aspect of systematics

Systematics

the study of the diversification of living forms, both past and present, and the relationships among living things through time.

cladogram

A cladogram is a simplified visualization of a taxon’s
evolutionary history, where character states are used to group related organisms. Typically shows a progression from ancestral to most
evolutionarily derived

Synapomorphy

a newly derived character state shared by all members of a
taxon

clade

a group containing a common ancestor and all taxa descending from it

Monophyletic

includes the most recent common ancestor and all of its descendants (aka “clade”)

Paraphyletic

includes the most recent common ancestor but not all of its descendants

Polyphyletic

grouping derived from more than one ancestor

Outgroup

Lineage that diverged prior to the clade of interest, used to anchor the tree.

Conservation

a careful preservation and protection of something

Use values for Conservation

Direct or indirect economic benefits derived from biological resources.

Non-use values for Conservation

Intrinsic value, existence value, or legacy for future
generations.

In Situ Conservation

Protecting species directly within their natural ecosystem
habitats.

Ex Situ

Preserving components of biological diversity outside natural
habitats.

Endemism

Species naturally restricted to a specific geographic region.

United Nations definition of biodiversity

The variability among living organisms from all sources… and the ecological
complexes of which they are part; this includes diversity within species,
between species, and of ecosystems.

Genetic Diversity

variation in the genetic make-up between individuals within a population and between populations

Organismal Diversity

the variation in a particular level of the taxonomic hierarchy (species, genera, and beyond)

Ecological (Ecosystem) Diversity:

ecological differences between habitats and biomes

Alpha Diversity

diversity within a particular area or ecosystem

Beta Diversity

differences in alpha diversity between ecosystems

Gamma Diversity

overall diversity for the different ecosystems in a broad region

Percentage of described, extant Vertebrates

3%

Percentage of described, extant Plants

16%

Percentage of described, extant Fungi

4%

Percentage of described, extant Invertebrates

66%

Percentage of described, extant viruses and prokaryotes

<0.01%

Percentage of described, extant protists

11%

Levels of taxonomy

Kingdom, Phylum, Class, Order, Family, Genus, Species

Holotype

organism on which species description is based

Isotype

Collected at the same place and time as holotype

Paratype

Collected at a different place or time than holotype

Species Richness

The number of species within a given sampling area

Species Evenness

How abundant each species is relative to the total number of individuals

Species-Area Relationships (Curves)

Empirical mathematical
relationship showing species richness increases predictably
with sampling area:

Phylogeny

the evolutionary history of a taxon

Phylogenetic Trees

Show inferred evolutionary relationships hypothesized by particular investigators

Species Richness

Raw count of number of species

Species Evenness

A measure of the relative abundance of the different species within a given area

Aristotle

Early classification via Scala Naturae (linear ladder of life
complexity)

Carolus Linnaeus

Father of modern taxonomy; established binomial

nomenclature (Genus + species).

Steps to Describe a Species:

Collect specimen → Detailed diagnosis &
description → Assign binomial Latin name & designate holotype → Peer-
reviewed publication.

Geological Hierarchy

Eons → Eras → Periods → Epochs

Origin of life and cyanobacterial
oxygenation of atmosphere

3.8–2.5 Ga

Origin of eukaryotic cells and early
fungal lineages

1.5–1.0 Ga

First land plants (Bryophytes) and
vascular plant radiation

470–420 Ma

Dominance of Seed Ferns,
Gymnosperms, & Angiosperm origin.

350–100 Ma

Origin of Earth

~4.5 Billion years ago

Precambrian Archaean Eon

• first life arises - chemoautotrophic prokaryotes (3.8 billion years ago)

• cyanobacteria begin photosynthesizing

Precambrian Proterozoic Eon

2.5bya- 570mya, Great Oxygenation Event, eukaryotes evolve (2bya), life dominated by small, soft-bodied eukaryotes until Cambrian Explosion

Cryogenian Period

720mya to 635mya, massive ice ages

Ediacaran/Vendian Period

• 635mya to 541mya

• Proliferation of multicellular, soft-bodied organisms

Phanerozoic Eon

542mya to present

Paleozoic Era

542-251mya, life moves to land, almost all invertebrate phyla appear

Cambrian Period

542-488 mya, ‘explosion’ brings diversification of form and algae, most major animal phyla appear, origin of general body plan for metazoans (animals), marine life still dominant

Ordovician Period

• 488-423mya

• shallow seas with abundant marine invertebrates

• first vertebrates with true bones (fish)

• first life on land, mass extinction

Silurian Period

• 423-416mya

• life on land progresses slowly

• first appearance of vascular plants

• major diversification of fish

Devonian Period

• 416-359mya

• significant diversification of life on land

• first stomata and cuticle like covering

• rhizoids

• tetrapods and arthropods colonize land

• mass extinction

Carboniferous Period

359-299mya, warm & humid climate, extensive forests generating massive coal reserves, high levels of oxygen in atmosphere (35%), reptiles appear (with amniotic egg)

Permian Period

299-251mya, supercontinent pangaea, starts with ice age, ends with mass extinction, drier climate, modern conifers appear

Mesozoic Era

251-65.5mya, dinosaurs, fragmentation of Pangaea leads to speciation

Triassic Period

• 251-200mya

• warm and dry climate

• recovery from permian extinction

• mammals and dinosaurs evolve

Jurassic Period

200-145mya, first birds appear, largest land animals of all time, cycads dominate plant world

Cretaceous Period

145-65.5mya, sea levels reach highest point, flowering plants (angiosperms) appear, age of reptiles, mass extinction event

Cenozoic Era

• 65.5mya-present

• mammals dominant on land

• Pleistocene Epoch (Last major ice age)

• Holocene Epoch (Post ice age, species radiation)

Reasons for maintaining biodiversity

• Ecosystem services

• economic & agricultural resilience

• ethical responsibility

Reasons for opposition of biodiversity

Economic opportunity costs, short-term vs long-term priorities, property rights & regulations

Beetles (Coleoptera)

Make up over 25% of all described animal species on Earth. Described by JBS Haldane.

End Ordovician Extinction

85%, 2my ice age

Late Devonian Extinction

• 80%

• not well understood - mass depletion?

Permian Extinction

• 95%

• Largest mass extinction

• occurred in pulses

• probably due to massive volcanism (Siberian Traps) that rapidly increased CO2

End Triassic Extinction

80%, volcanism

Cretaceous-Tertiary Extinction

• 75%

• K-T Event

• dinosaur extinction

• asteroid impact

• lowered sea levels

• intense volcanic activity

Anthropocene/Holocene Extinction

• potential human-caused mass extinction

• rates up to 100x higher than background rates

• timing corresponds with industrialization

Mass Extinction Events

relatively short events resulting in massive species loss, indiscriminate, opens niches for adaptive radiation and greater diversity

Described, Extant Species

1.9M out of ~8.7M estimated