BIOL: 1412 Unit 1

Eukaryotes evolved from ___

Archaea

In single-celled species, mitosis increases the ___ of individuals

number

In multicellular species, mitosis increases the ___ of individuals

size

What defines an animal?

• Multicellular

• Heterotrophic

• Internal Digestion

• Movement and Nervous Systems

Which of the five characteristics that define animals is unique to animals?

Movement and nervous systems and muscle tissues

__ suggests that sponges are the earliest relative to humans

morphologic evidence

__ suggests that ctenophores are the earliest relative to humans

genomic evidence

What is the closest relative to animals?

Choanoflagellates

What is the Cambrian “Explosion” known for?

a large increase in diversity

Characteristics of the Cambrian explosion

• Rapid “burst” of diversification

• Marine organisms (sponges, crustaceans and sea star relatives, mollusks, worms, and chordates)

• modern-day phyla appeared and evolved

• punctuated equilibrium

• Punctuated by short periods or rapid diversification

• Land not yet colonized

Relative Stasis

rate of evolution is relatively slow and constant

Why the Cambrian?

• Increase in global O2

• Increase in ocean Ca2+

• Expansive continental shelf

  • Shallow lagoons

  • Increased habitat

• Evolution of Hox genes

  • body pattern changes

Ordovician

• modern spinal column takes form—>first fishes

• then, plants colonize land

• finally, animals colonize land

Early Ordovician

• first fishes

  • evolution of armored plates

Late Ordovician

• bony jaws evolved

  • large predators

  • Acanthodians and Placoderms formed

Acanthodians

ancestors of many sharks

Placoderms

ancestors of bony fishes

Devonian

• Diversification of sharks and bony fishes

• Placoderms extinct by the end

• First lobe-finned fishes evolve

  • land begins to be colonized

• Closer related to humans than other fish

End of Triassic Period

• bony fishes diversify

• then, extinction event

Jurassic Period

• Increase in body size

• Following extinction event

  • open habitat/niches

  • more large reptiles etc. for prey

Cretaceous Period

• closest ancestors of modern fishes evolved

• more large predators

  • upwards jaw, long teeth, fish swallowed whole

Cretaceous-Paleogene

• K-Pg boundary

• dinos extinct

• radiation of bony fishes

  • extinction of ammonites help?

Order of periods

Cambrian < Ordovician < Devonian < Triassic < Jurassic < Cretaceous < Cretaceous-Paleogene

When did lobe-finned fishes arise and diversify?

Devonian period

When did we see the first fish colonize land?

~end of Devonian

What led to evolution of tetrapods?

Lobe-finned fishes colonizing land and evolving (skeletal and muscle modifications)

What are examples tetrapods?

amphibians, mammals, birds & crocodilians, and squamates (lizards and snakes)

What was the first real tetrapod to colonize land?

amphibians

What features changed when amphibians colonized land?

• Gravity - muscular and skeletal modifications

• Desiccation - skin (barrier)

• Different oxygen medium - O2 dissolved in water vs in the atmosphere

What period did the first ancestors of mammals, birds, crocodilians, and reptiles appear in?

The Pennsylvanian Period

What was the ancestral lineage that led to birds, crocodilians, and reptiles?

Sauropsid

What did sauropsids give rise to?

• Dinosaurs

• Modern birds

• Crocodilians

• Snakes, lizards

What did the K-Pg extinction wipe out?

non-avian dinosaurs

What was the ancestral lineage that led to mammals?

Synapsids

How was the Jurassic period significant to mammals?

Mammals started to look like modern-day mammals

What did the K-Pg extinction do for mammals?

• Opened niches

  • mammals capitalize on extinction of dinosaurs

• Diversification of forms and functions

Centralization

Components are in the center of the body

• ex: central nervous system

Cephalization

See a lot of important organs are toward the head

Centralization and cephalization are examples of what?

Trends in animal evolution

Order of extinction events

Late Ordovician, Late Devonian, Permian-Triassic, Triassic-Jurassic, Cretaceous-Paleogene

What caused the Late Ordovician extinction?

Volcanism and anoxia

What caused the Late Devonian extinction?

Ocean anoxia and global cooling fluctuations

What caused the Permian-Triassic extinction?

Global warming and ocean acidification

What caused the Triassic-Jurassic extinction?

Volcanic eruptions, global warming, and ocean anoxia

What caused the Cretaceous-Paleogene extinction?

Asteroid

What is homeostasis?

The stability of the internal environment of an individual, such as a constant body temperature and the physiological or behavioral feedback responses that maintain that stability

Why do individuals employ homeostasis?

Because their outside environment is likely different

Homeostasis parameters

• Temperature

• pH

• Blood glucose

• Blood pressure

• Heart and respiratory rate

• Behavioral feed back

• O2

• CO2

• Na+

• Ca+

Why is thermoregulation important?

• External extreme environment temperatures

• Enzymes

• Metabolisms at different temperatures is challenging

Non-biological thermoregulation

• Temp decreases—response to raise temp

• Negative feedback system

  • Mechanism brings it back to the original point

Biological thermoregulation

• brain regulates

  • shivering body—raise temperature

  • Blood vessels keep blood close to core

___: vessels near surface constrict

cold

___: vessels near surface dilate

warm

What is the Q10 temperature coefficient?

A measure of sensitivity of a reaction or physiological process to a change in temperature (within a limited range)

• Q10 = 9/3=3

Regulators

Animals that keep a steady internal body temperature

Conformers

Animals that vary their body temperature along with the environment

Examples of regulators

Birds and mammals

Examples of conformers

Frogs, lizards, and fish

Brown adipose tissue

a specialized type of body fat that burns energy to generate heat and help maintain body temperature

White adipose tissue

the most common type of body fat, and it stores extra energy as fat molecules

Nonshivering thermogenesis

a metabolic process where the body creates heat without physical muscle shaking

What is an example of nonshivering thermogenesis?

Burning brown adipose (ex: infants)

Endotherm (homeotherm)

• An animal that gets heat primarily from internal sources (metabolism)

• May or may not be successful at maintaining a constant temperature

Ectotherm (poikilotherms)

• An animal that obtains heat primarily from external sources

• May have body temperatures higher or lower than external temperature

___animals rely on behavioral thermoregulation

Smaller

___animals rely on structural and physiological thermoregulation

Larger

Examples of behavioral thermoregulation

• Moves to microclimates

• Avoid wind

• Humans—clothing

Examples of structural and physiological thermoregulation

• Develop structures to help—adaptations

• E.g. hair (composition- with or without more air spaces)

• E.g. countercurrent mechanisms

• E.g. sweating and panting

What are microenironments?

Environments within a larger habitat that contain different conditions

Examples of microenvironments

• Shade

• Sunbathing structures

• Snow

• Root systems

• Thermoclines

• Water depth

• Etc.

What are features of counter current heat exchange?

• Very close and parallel to each other

• Transports in two different directions

A ___ surface means ___ heat is (usually) lost [but in few situations gaines]

larger; more

Negative feedback regulation

• Stressor causes deviation from set point/range

• Physiology is changes to brink parameters back to set point range

• Stabilizes systems

Positive feedback regulation

• Speeds up/amplifies process/change that is occurring

• Not typically involved in homeostasis

• Some events causes feedback to stop

• E.g. mammal birth

• E.g. fever

Functions of the respiratory system

• Gas exchange

• Olfaction (breathe and smell)

• pH balance

• Blood flow—pressure gradients

• Communication

What are the major receptors in the feedback mechanism of the respiratory system?

Chemoreceptors (picks up on H+ concentration)

Why do animals need oxygen to survive?

O2 is the final electron acceptor in the ETC

What are the primary goals of the respiratory system?

To deliver oxygen to the mitochondria and remove metabolic waste product