Verterbates and Speciation Flashcards
Synamorphy
Definition
a common feature shared by all descendants of a common ancestor after a divergence
Chordates
Subcategories
- Vertebrates
- Invertebrate:
- Cephalochordates (Lancelets)
- Urochordata (Tunicates)
Chordates
Common Characteristics
- notochord (stiffened material down centre that allows movement
- dorsal, hollow nerve cord
- postanal tail
- pharygeal slits
Cephalochordates
- notochord down centre
- move left to right
Urochordata
-suck water through body
Vertebrates
Common Characteristics
- Vertebral Column, tube of hollow bones that enclose and protect the dorsal nerve chord
- Head/Cephalisation, distinct and well differentiated head with skull and brain
- Neural Crest, unique group of embryonic cells that contribute to development of spinal chord
- Internal Organs, liver kidneys ane endocrine system
- Closed Circulatory System
- Efficient Respiration and Excretion
- Paired Appendages
- Endoskeleton
Crown Group Vertebrates
- sharks
- ray-finned fish
- amphibians
- primates
- rodents and rabbits
- crocodiles
- dinosaurs and birds
Fish
Subcategories
- jawless
- cartilaginous
- bony
Fish
Common Characteristics
- Gills, as water passes over the gills it hits fine filaments of blood vessels into which oxygen diffuses
- Vertebral Column, internal skeleton with a spine that surrounds the dorsal nerve chord
- Single-Loop Blood Circulation, blood pumped from heart to gills to rest of the body and back to the heart
- Nutritional Deficiencies, unable to synthesise aromatic amino acids so must consume them in their diet
Jawless Fish
- agnathens
- lack bony skeleton
- cylindrical shape
- scavengers (hagfish) OR filter feeders (lampreys)
- parasitic lampreys attatch to the sides of bony fish and suck nutrients from the host circulatory system
Cartilaginous Fish
- skeleton made of cartilage not bone
- superior design for swimming
- array of fins (cadval, dorsal, ventral & front pectoral and rear pelvic pair)
- 3 well developed senses (sense electric currents, smell, pressure sensitive cells on insides of body)
- advanced reproduction
- some shark eggs are internally fertilised
Bony Fish
- evolved in freshwater
- highly mobile fins
- symmetrical tails
- lobe finned and ray finned fish arose from bony fish
- swim bladder, for buoyancy it keeps fish suspended at any depth (in modern fish it is an independent organ that is filled/drained of gas from the blood)
- Lateral Line System, fully developed series of sensory organs to aid orientation and detection of objects
- Gill Cover, hard plate/operculum covers gills on each side/head used to pump water over gills while stationary
Amphibia
Evolution
- direct descendants of lobe finned fish
- most numerous land animals
- 3 orders:
- Anura (frogs & toads)
- Caduata (salamanders & newts)
- Gymnophiona/Caecilians (no legs)
Amphibia
Common Characteristics
- Legs, apart from caecilians which have adapted for burrowing
- Cutaneous Respiration, respiration through the skin supplements lungs & limits body size
- Lungs, pair of lungs they breathe by lowering the mouth and raising it back up to force in air
- Pulmonary Veins & Partially Divide Heart, splits blood circulation into two paths
- Metamorphosis, adaptation to water or land environment
Reptiles
Evolution
- evolved from amphibian
- legs arranged to support body weight increasing efficiency
- lungs and heart altered
- skin covered with dry scales
- eggs encased in water tight covers
Reptiles
Common Characteristics
- Amniotic eggs, watertight & contains food & a series of 4 membranes making the egg an independent life support system
- Dry Skin, scales prevent water loss and develop as surface cells fill with keratin
- Thoracic Breathing, expand & contract rib cage to suck in/force out air from lungs capacity is limited by lung volume
Birds
Evolution
- similar to reptiles
- BUT many say that they evolved from dinosaurs
Birds
Common Characteristics
- Feathers, modified reptilian scales provide lift for flying and insulation
- Flight Skeleton, thin hollowed out bones many of which are fused together forming a sturdy frame to anchor muscles during flight
- Breast Muscles, 30% of body weight to provide strength for flight
- Efficient Respiration
- Efficient Circulation, dividing wall in the heart is complete
- Endothermy, 40-42C body temperature
Mammals
Evolution
emerged 220mya
Mammals
Subcategories
- Monotremes, egg laying
- Marsupials, young born early in development and complete growth in the pouch
- Placental, lack pouches and suckle young
Mammals
Common Characteristics
- Hair, key for heat regulation and fur allowed invasion into colder climates / camouflage
- Milk Producing Glands, allows mammal to suckle young
- Endothermic, can be active at day or night
- Placenta, females carry young in the uterus during development
- Teeth, heterodont dentition specialised to eating habits
- Digestive System for Eating Plants, herbivores can’t break down cellulose so rely on a mutualistic relationship with intestinal bacteria with a cellulose digesting enzyme
- Horns and Hooves, made of keratin
What are the three main mechanisms of speciation?
- polyploidy
- allopatric/geographic
- sympatric/ecological
Allopatric/Geographic Speciation
- one population
- part of the population moves to a different area
- gene flow between the two groups ceases
- OR the population can be separated by a barrier e.g. a river preventing gene flow between the two groups
Ring Species Concept
- allopatric
- species expands around an area of unsuitable habitat
- as the species spreads around the ring it evolves over time
- all around the ring, adjacent variations of the species are able to interbreed
- but when the end of the ring reaches the beginning again the species has changed so much that it can no longer interbreed with the original species
Karyological Revolution
change in karyotype
Karyotype
number of chromosomes in the somatic cell
Speciation by Polyploidy
- two species interbreed producing a largely sterile hybrid
- the two original species cannot interbreed with the hybrid
- if the hybrid is fertilised it can reproduce, a new species
Speciation by Polyploidy
Example
-wild sea cabbage (18n) wild sea cabbage gamete (9n) -turnip (20n) -turnip gamete (10n) -turnip + cabbage = hybrid (19n) -fertilisation of hybrid -> swede (38n)
Sympatry/Parapatry
-a reproductive barrier arises (i.e. speciation occurs) eventhough gene flow between the two populations remains possible
Ecological Speciation
- different members of the same population adapt to occupy different niches in the same habitat
- as they become specialised a hybrid of the two groups is out competed in both niches by the two groups as it isn’t optimised for either niche
- hybrids don’t survive to reproduce so the two groups continue to breed independently and evolve independently
Speciation
Definition
the formation of a new species
The Biological Species Concept
focus on reproductive isolation
i.e. a species is defined as a group of organisms that can interbreed to produce fertile offspring
Reproductive Isolation
Pre-Mating
-individuals may meet but don’t mate
Reproductive Isolation
Post-Mating, Pre-Zygotic
- no sperm transfer
- gamete incompatibility
- gamete isolation
Reproductive Isolation
Post-Mating, Post-Zygotic
- F1 inviability / infertility
- F1 sterility
Speciation and Darwin’s Theory of Evolution
- undermines the stability of species
- populations can be observed at different stages of speciation
- this makes the identification of species arbitrary/subjective as the organisms that make up the species are always changing
Social Learning
- learning influenced by observation of / interaction with another individual or its products
- learning facilitated by observation of / interaction with another individual or its products
Demonstrator
the individual being learnt from
Observer
the individual who is learning
Social Transmission
the acquisition of a behavioural trait T by an individual A, exerts a positive causal influence on the rate at which another individual B acquires/performs T
Imitation
- (broad sense) copying anothers behaviour
- (narrow sense) observe the body movements of another individual and replicate them exactly to produce the same behaviour, i.e. to learn to do an act from seeing it done
Culture
-group level behaviour patterns shared by members of a community that rely on socially learned and transmitted behaviours
When is it advantageous for animals to learn from others?
- depends on the rate of environmental change:
- -slow - unlearned behaviour
- -moderate - social learning
- -fast - asocial learning, as information becomes outdated so quickly it cant be passed on fast enough to be useful before the environment changes again
Core Methodology
Studying in the Field
- high validity
- low reliability and control
- uncontrolled conditions
- actual behaviour
Core Methodology
Lab Experiment
- high reliability and control
- low validity
Traditional Demonstrator Observer Paradigm
- observer placed with demonstrator during observation phase
- then during the test phase the observer is observed alone to see if they exhibit the behaviour
- as a control, an observer is also placed with a demonstrator that doesn’t perform the behaviour, this observer is then also observed in the observation phase
Traditional - Multiple Demonstrators
- one observer sees multiple demonstrators performing the behaviour
- sometimes animals are more likely to learn a behaviour if they see multiple demonstrators doing it
Traditional - Multiple Observers
-multiple observers can learn a behaviour from the same demonstrator
Linear Transmission Chain
- behaviour passed along a chain of individuals
- first observer becomes demonstrator for the second observer etc.
Replacement Transmission Chain
- start with a group of demonstrators
- one observer introduced and learns the behaviour
- one of the original demonstrators is replaced with a new observer
- this continues until there are no original observers left nut the group is stlll able to complete the behaviour
What does an observer have to do to imitate?
- solve the correspondence problem
- translating observation into motor movement
Local Enhancement
- similar to imitation but not the same
- after/during a demonstrators presence/interaction with objects at a particular location, an observer is more likely to visit that area and then learn the behaviour itself as a result rather than copying
Open Diffusion
- one original demonstrator in the population
- behaviour spreads through the population with initial observers becoming demonstrators
Two Action Test
FINISH SOCIAL LEARNING CARDS
