How Biological Diversity Evolves The Origin of Species The Evolution of Biological Novelty Earth History and Macroevolution Classifying the Diversity

How Biological Diversity Evolves The Origin of Species

The Evolution of Biological Novelty

Earth History and Macroevolution

Classifying the Diversity of Life

Biology and Society: The Sixth Mass Extinction

• Over the past 540 million years, the fossil record reveals five periods of extinction when 50–90% of living species suddenly died out.

© 2013 Pearson Education, Inc.

A critically endangered species: the black and white ruffed lemur

• Our current rate of extinction, over the past 400 years, indicates that we may be living in, and contributing to, the sixth mass extinction period.

• Mass extinctions pave the way for the evolution of new and diverse forms, but it takes millions of years for Earth to recover.

Biology and Society: The Sixth Mass Extinction


Figure 14.1

PATTERNS OF EVOLUTION

• In the 150 years since the publication of Darwin’s book On the Origin of Species by Means of Natural Selection, new discoveries and technological advances have given scientists a wealth of new information about the evolution of life.

• The diversity of life evolved through speciation, the process in which one species splits into two or more species.

THE ORIGIN OF SPECIES


Figure 14.2

Diversity within one speciesSimilarity between different species

Species Species are groups of populations whose

members possess similar anatomical characteristics and have the ability to interbreed and produce fertile offspring.

Any organism which divides by asexual reproduction can only produce it’s own kind.

Reproductive Barriers between Species

• Prezygotic barriers prevent mating or fertilization between species.

• Temporal isolation – timing doesn’t work

• Habitat isolation – species live in different places (note: animals of different species in a zoo, even if they can mate and have fertile offspring are still considered different species)

• Behavioral isolation – one species doesn’t like another ex: female fireflies only mate with males who emit light in a particular pattern.

• Mating attempts: mechanical or gametic isolation


Figure 14.3

VIABLE, FERTILE OFFSPRING

Hybrid breakdown

FERTILIZATION (ZYGOTE FORMS)

INDIVIDUALS OF DIFFERENT SPECIES

MATING ATTEMPT

Reduced hybrid fertility

Reduced hybrid viability

Temporal isolation

Habitat isolation

Behavioral isolation

Mechanical isolation

Gametic isolation

Prezygotic Barriers

Postzygotic Barriers

No Barriers

Figure 14.4

Temporal Isolation Habitat IsolationPREZYGOTIC BARRIERS

Mechanical Isolation Gametic IsolationBehavioral Isolation

• Postzygotic barriers

• interspecies mating occurs but offspring are infertile. Like a mule.

Reproductive Barriers between Species


Figure 14.5

Hybrid BreakdownReduced Hybrid FertilityReduced Hybrid Viability

POSTZYGOTIC BARRIERS

Donkey

Mule

Horse

Mechanisms of Speciation

• A key event in the potential origin of a species occurs when a population is somehow cut off from other populations of the parent species.

• Species can form by

–allopatric speciation, due to geographic isolation, or

–sympatric speciation, The formation of a new species in populations in the same geographic area.


Figure 14.6

Allopatric speciation Sympatric speciation

Allopatric Speciation

• Geologic processes can

– fragment a population into two or more isolated populations and

– contribute to allopatric speciation.


Figure 14.7

Ammospermophilusharrisii

Ammospermophilusleucurus

• Speciation occurs with the evolution of reproductive barriers between

– the isolated population and

– its parent population.

• Even if the two populations should come back into contact at some later time, the reproductive barriers will keep them as separate species.

Allopatric Speciation


Figure 14.8

Geographicbarrier

Populationsinterbreed

Time

Populationsbecomeallopatric

Populationsbecomesympatric

Populationscannotinterbreed

Reproductive isolation: Speciation has occurred

Gene pools merge: No speciation

Sympatric Speciation

• Sympatric speciation occurs in populations that live in the same geographic area.

• An accident during cell division that results in an extra set of chromosomes is a common route to sympatric speciation in plants.

• Many polyploid species arise from the hybridization of two parent species.


• Many domesticated plants are the result of sympatric speciation, including

– oats,

– potatoes,

– bananas,

– peanuts,

– apples,

– coffee, and

– wheat.

Sympatric Speciation


What Is the Pace of Speciation?

• There are two contrasting patterns for the pace of evolution:

1. the gradual pattern, in which big changes (speciations) occur by the steady accumulation of many small changes, and

2. the punctuated equilibria pattern, in which there are

– long periods of little apparent change (equilibria) interrupted (punctuated) by

– relatively brief periods of rapid change.


Figure 14.10

Punctuatedpattern

Gradualpattern

Time

THE EVOLUTION OF BIOLOGICAL NOVELTY

• What accounts for the dramatic differences between dissimilar groups?


Adaptation of Old Structures for New Functions

• Birds

– are derived from a lineage of earthbound reptiles and

– evolved flight from flightless ancestors.


Figure 14.11

Wing claw(like reptile)

Teeth(like reptile)

Long tail withmany vertebrae

(like reptile)

Feathers

FossilArtist’s reconstruction

• An exaptation is

– a structure that evolves in one context but becomes adapted for another function and

– a type of evolutionary remodeling.

• Exaptations can account for the evolution of novel structures.

• Ex: if a fish lives in a lake that dries up, they could use their fins to “walk” to another body of water.



• Bird wings are modified forelimbs that were previously adapted for non-flight functions, such as

– thermal regulation,

– courtship displays, and/or

– camouflage.

• The first flights may have been only glides or extended hops as the animal pursued prey or fled from a predator.



Evo-Devo: Development and Evolutionary Novelty

• Evo-devo, evolutionary developmental biology, is the study of the evolution of developmental processes in multicellular organisms.


• Homeotic genes are master control genes that regulate

– the rate,

– timing, and

– spatial pattern of changes in an organism’s form as it develops from a zygote into an adult.

• Mutations in homeotic genes can profoundly affect body form.

Evo-Devo: Development and Evolutionary Novelty


EARTH HISTORY AND MACROEVOLUTION

• Macroevolution is closely tied to the history of Earth.


Geologic Time and the Fossil Record

• The fossil record is

– the sequence in which fossils appear in rock strata and

– an archive of macroevolution.


Figure 14.14

A sedimentary fossil formedby minerals replacing theorganic matter of a tree

Trace fossils: footprints, burrows, or other remnants of an ancientorganism’s behavior

A 45-million-year-oldinsect embeddedin amber

Tusks of a 23,000-year-old mammothdiscovered in Siberian ice

A researcherexcavating afossilizeddinosaurskeleton fromsandstone

Our current geologic era is the CENOZOIC

GeologicTime Period Epoch

Age (millionsof years ago) Some Important Events in the History of Life

Table 14.1 The Geologic Time Scale

Cenozoicera

Quaternary

Tertiary

Recent

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Paleocene

0.01

1.8

5

23

34

56

65

Historical time

Ice ages; humans appear

Origin of genus Homo

Continued speciation of mammals andangiosperms

Origins of many primate groups, including apes

Angiosperm dominance increases; origins of mostliving mammalian orders

Major speciation of mammals, birds,and pollinating insects

145

200

251

Mesozoicera

Cretaceous

Jurassic

Triassic Cone-bearing plants (gymnosperms) dominate landscape;speciation of dinosaurs, early mammals, and birds

Flowering plants (angiosperms) appear; many groups oforganisms, including most dinosaur lineages, becomeextinct at end of period (Cretaceous extinctions)

Gymnosperms continue as dominant plants;dinosaurs become dominant

Paleozoicera

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

Precambrian

299

359

416

444

488

542

600

635

2,100

2,700

3,500

4,600

Extinction of many marine and terrestrial organisms(Permian extinctions); speciation of reptiles; origins ofmammal-like reptiles and most living orders of insects

Extensive forests of vascular plants; first seedplants; origin of reptiles; amphibians become dominant

Diversification of bony fishes;first amphibians and insects

Early vascular plants dominate land

Marine algae are abundant; colonization of land bydiverse fungi, plants, and animals

Origin of most living animal phyla (Cambrian explosion)

Diverse algae and soft-bodied invertebrate animals appear

Oldest animal fossils

Oldest eukaryotic fossils

Oxygen begins accumulating in atmosphere

Oldest fossils known (prokaryotes)

Approximate time of origin of Earth

Relative Time Span

Paleozoic

Mesozoic

Cenozoic

Pre-cambrian

PANGEA The name of the supercontinent which

formed near the end of the Paleozoic era.

Plate Tectonics and Macroevolution

• The continents are not locked in place.

– Continents drift about Earth’s surface on plates of crust floating on a flexible layer of hot, underlying material called the mantle.

– When these plates move, they cause earthquakes


Figure 14.16

• About 250 million years ago,

– plate movements formed the supercontinent Pangaea,

– the total amount of shoreline was reduced,

– ocean basins increased in depth,

– sea levels dropped,

– the dry continental interior increased in size, and

– many extinctions occurred.



Figure 14.17

Pangaea is formed.

Pangaea splits intoLaurasia and Gondwana.

India collides with Eurasia. Cen

ozo

icM

eso

zoic

Pal

eozo

ic251

mil

lio

n y

ears

ag

oP

rese

nt

135

65

• Plate tectonics helps to explain

– why Mesozoic reptiles in Ghana (West Africa) and Brazil look so similar and

– how marsupials were free to evolve in isolation in Australia.

– http://youtu.be/cC8k2Sb1oQ8



http://youtu.be/cC8k2Sb1oQ8

Mass Extinctions Mass extinctions are typically followed by

explosive diversification

CLASSIFYING THE DIVERSITY OF LIFE

• Systematics focuses on

– classifying organisms and

– determining their evolutionary relationships.


CLASSIFYING THE DIVERSITY OF LIFE

• Taxonomy is the

– identification,

– naming, and

– classification of species.

• Systematics includes taxonomy.


Naming Species

• Each species is assigned a two-part Latinized name or binomial, consisting of

– the genus and

– a name unique for each species.

• The scientific name for humans is Homo sapiens,

– a two part name, italicized,

– given a Latin ending, and

– with the first letter of the genus capitalized.


Figure 14.19

Jaguar (Panthera onca)

Lion(Panthera leo)

Tiger(Panthera tigris)

Leopard(Panthera pardus)

• The taxonomic hierarchy extends to progressively broader categories of classification, from genus to

– family,

– order,

– class,

– phylum,

– kingdom, and

– domain.

Hierarchical Classification


Figure 14.20

Leopard (Panthera pardus) Species

Pantherapardus

GenusPanthera

FamilyFelidae

OrderCarnivora

ClassMammalia

PhylumChordata

KingdomAnimalia

DomainEukarya

Know these in general

Domain-Kingdom-phylum-class-order-family-genus-species

Classification and Phylogeny

• The goal of systematics is to have classification reflect evolutionary relationships.

• Biologists use phylogenetic trees to

– depict hypotheses about the evolutionary history of species and

– reflect the hierarchical classification of groups nested within more inclusive groups.

– Analogous structures are evidence of convergent evolution


Figure 14.21

Panthera pardus

(leopard)

SpeciesGenus

Felidae

Order

Carnivora

Family

Canis

Lutra

Panthera

Mephitis

Canidae

Mustelidae

Canis lupus(wolf)

Canis latrans

(coyote)

Lutralutra

(Europeanotter)

Mephitis mephitis

(striped skunk)

Molecular Biology as a Tool in Systematics

• Molecular systematics

– compares nucleotide and amino acid sequences between organisms and

– can reveal evolutionary relationships.

• The more recently two species have branched from a common ancestor, the more similar their nucleotide and amino acid sequences should be.


Molecular Biology as a Tool in Systematics

• Some fossils are preserved in such a way that DNA fragments can be extracted for comparison with living organisms.


Figure 14.22

The Cladistic Revolution

• In cladistics, organisms are grouped by common ancestry.

• A clade consists of an ancestral species and all its evolutionary descendants and forms a distinct branch in the tree of life.


Figure 14.23

Hair, mammaryglands

Long gestation

Gestation

Duck-billedplatypus

Iguana Outgroup(reptile)

Ingroup(mammals)

Beaver

Kangaroo

• Cladistics has changed the traditional classification of some organisms, including the relationships between

– dinosaurs,

– birds,

– crocodiles,

– lizards, and

– snakes.

The Cladistic Revolution


Figure 14.24

Lizardsand snakes

Crocodilians

Saurischiandinosaurs

Ornithischiandinosaurs

Pterosaurs

Birds

Commonancestor ofcrocodilians,dinosaurs,and birds

Classification: A Work in Progress

• Phylogenetic trees are hypotheses about evolutionary history.

• Linnaeus divided all known forms of life between the plant and animal kingdoms.

• This two-kingdom system prevailed in biology for over 200 years.



• In the mid-1900s, the two-kingdom system was replaced by a five-kingdom system that

– placed all prokaryotes in one kingdom and

– divided the eukaryotes among four other kingdoms.


• In the late 1900s, molecular studies and cladistics led to the development of a three-domain system, recognizing

– two domains of prokaryotes (Bacteria and Archaea) and

– one domain of eukaryotes (Eukarya).



http://youtu.be/fQwI90bkJl4

Documents

How Biological Diversity Evolves The Origin of Species The Evolution of Biological Novelty Earth History and Macroevolution Classifying the Diversity