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1. Galapagos fur seal- Arctocephalus galapagoensis

2. Steller sea lion- Eumetopias jubatus

3. Northern fur seal- Callorhinus ursinus

4. Leopard Seal- Hydrurga leptonyx

5. Guadalupe fur seal- A. townsendi

6. Southern sea lion- Otaria byronia

7. Crabeater Seal- Lobodon carcinophaga

8. Grey Seal- Halichoerus grypus

9. California seal lion- Zalophus californianus

10. Hawaiian monk seal- Neomonachus schauinslandi

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Microevolution

Microevolution has occurred in pinnipeds due to allele frequencies that have changed over time and how directional selection has occurred over time as well

Over time, newer species of pinnipeds have evolved from the common ancestral species

The changes in each species is due to microevolution which lead to macroevolution which has emerged new species over time

Genetic Drift has also resulted in the evolution of these organisms because there have been changed in the allele frequencies within the pinnipeds

In addition, population bottleneck has occurred in the grey seal and the harbor seal which has drastically reduced the size of these two organisms populations

There has been a decrease in genetic diversity/variation in these pinnipeds because of genetic drift within the pinniped populations

Also, population bottlenecks and nonrandom mating has occurred within the New Zealand Sea Lion population which has impacted the genetic variation

This sea lion has had a reduced population size and there has been an increase in interbreeding which has affected their long-term chance for survival

http://legacy.hopkinsville.kctcs.edu/instructors/jason-arnold/vli/module3evolution/Module3Evolution4.html
https://academic.oup.com/jhered/article/107/5/392/2622901

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This peptide sequence chart that compares the walrus, eared seals, and earless seals (at the bottom of the chart) shows the similarities in the protein sequence of these two organisms

This chart shows the amino acid sequence in both of these organisms and how each chain is very similar in structure

The walrus, eared, and earless seals have very similar and almost identical amino acid sequences which supports the fact that they are very similar and have evolved from each other

When there are many amino acids that are the same, that means their DNA sequences are also very similar

DNA also codes for for the building of proteins

The amino acid sequences are determined by the nucleotide sequences in the DNA and since the walrus, eared, and earless seal have similar amino acids, their DNA and nucleotide sequences have to also be similar

There are a few differences in each of the organisms protein sequence but overall the sequences are similar proving that these three organisms are closely related

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Descent with Modification

Newer species of Pinnipeds, Otarids, Odebenids, and Phocids, have become modified descendants of their ancestral species

These similar species show different characteristics in their different habitats and locations

Each generation of pinnipeds sexually reproduced which created a mixing of genes from the parents which creates genetic variation in the common ancestors descendants

There is a change in the gene frequency in each generation which causes variation in the offspring of each generation

Pinnipeds' DNA has changed over time in each generation. Their nucleotide sequence has evolved as time has went on and since each organism has developed from their ancestral species

Directional Selection

Pinniped species have evolved through directional selection because different phenotypes have been favored over the pinnipeds evolutionary history to bring about new traits and help them survive

There have been many new phenotypes and physical characteristics that have occurred in pinnipeds

For example environmental factors have contributed to they  way pinnipeds have evolved

Walruses have the phenotype, or expressed physical characteristic, for their tusk size

Earless seals have the phenotype for longer phalanges and curved flippers for mobility in the water and stabilization in the environment that they live in

Eared seals have the phenotype for straighter flippers and shorter phalanges so they can stand up on rocks when they haul out on land

Natural selection has favored the phenotypes in the pinnipeds who have survived throughout their evolutionary history and this has caused a change in which traits are favored in each organism

https://biologydictionary.net/directional-selection/
https://sciencing.com/difference-between-natural-selection-descent-modification-17942.html

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Divergent Evolution

Over time, Pinnipeds have become more and more dissimilar in their internal and external characteristics

Pinnipeds have evolved from a common ancestor but have become different species over time

The pinnipeds phylogenic tree shows how all of the pinnipeds have evolved from one ancestor

They all have developed different external characteristics that help each of them individually

For example, their head shapes have become different over time because they all have different characteristics

The walrus has a more roundish-square head because of its need for tusks

Earless seals have a round head because they do not have ears and have an arched snout

Eared seals have a spindle shaped head because they have ears

Also, their flippers have changed over time to become more curved for their functional needs

The earless seal has the most curved flippers out of all three of these organisms because they extend backward and cannot be brought underneath their bodies

All pinnipeds have evolved from one common ancestor but have become very different structurally over time which supports the fact that they went through divergent evolution

http://what-when-how.com/marine-mammals/pinniped-evolution-marine-mammals/

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Gradual Speciation

Pinnipeds have gradually diverged over time and have developed different characteristics for the needs of that organism throughout its evolutionary history

Small changes have occurred in the earless seal, eared seal, and the walrus as time has passed

Each organism developed traits to help them survive in their specific environment and to continue to reproduce

The needs of each organism are very different so they each have changed and evolved from the one common ancestor that they all shared

Sympatric Speciation

Pinnipeds have gone through sympatric speciation because they have shared the same type of habitat but have become reproductively isolated so that if each group tried to mate with one another, they will not produce fertile offspring; which leads to the further divergence of each group of organisms

New species have evolved from a common ancestral species that were located in the same region and have shared the same habitat

http://www.yourarticlelibrary.com/biology/mechanisms-of-speciation-gradual-speciation-and-abrupt-of-instantaneous-speciation/27223

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1. Name of fossil: Chin of Pelagiarctos thomasi; Age: 700,000 years old

2. Name of fossil: Skull of Allodesmus kelloggi; Age: 15-17 million years old

3. Name of fossil: Skull of the modern day female Callorhinus ursinus; Age: 22-25 Ma

4. Name of the fossil: Femora of the Oligocene; Age: 45-49 Ma in age.

5. Name of fossils: Jaws and teeth of many different pinnipeds; Ages: Dated back to 15-27 Ma

http://coastalpaleo.blogspot.com/search/label/pinnipedia

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This phylogenic tree shows the connection between the family Otariidae, Odobenidae, and Phocidae.

There was a common ancestor which connected all of the species together

All of these species have "risen" from this one common ancestor that they all share at the bottom of the tree trunk

There is an evolutionary relationship between those three speices

These three species are very close in distance which shows how closely related they all are

The most recent common ancestor is shared between all three of these organisms because they form a "triangle" shape and shows that they are the most closely related organisms in this tree

Walruses and eared seals evolved from a bear ancestor and the true seals evolved from an otter carnivore

The tree shows that all pinnipeds have evolved from a monophyletic group

Walruses share a closer relationship with earless seals (Phocidae) than with eared seals (Otaridae)

http://what-when-how.com/marine-mammals/pinniped-evolution-marine-mammals/
http://palaeo.gly.bris.ac.uk/Palaeofiles/Pinnipeds/evolution.html

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Pinnipeds all have a similar number of chromosomes

Otariids have 2n=36 diploid chromosomes; a total of 18 pairs of chromosomes

Odebenids have 2n=32 chromosomes; a total of 16 pairs of chromosomes

Phocidae have chromosomes numbers ranging from 2n=34 to 2n=32; a total of either 16 or 17 pairs of chromosomes

These chromosome numbers show how closely related these organisms are because they have a range of 32 to 36 total diploid cells

Also in their karyotypes, the centromeres are almost exactly in the same place and the banding patterns are very similar in structure

This evidence can show how the structure of these species chromosomes are very similar in each of these organisms' karyotypes

In addition, having similar numbers of diploid chromosomes, very few differences in their chromosome numbers, and similar karyotypes supports the fact that these species are related

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Anatomy of the pinnipeds

The pinniped families have evolved to fit their needs in the water, on land, finding food, and reproducing

Pinnipeds started off as organisms with the sequence 1 bone, 2 bones, many bones, falangees

They also had fingers that were closer together and short in lenght

Their heads were also flat and rounded for the ability to glide in the water

They also had short front teeth chewing and breaking down their food and biting their prey

Over time, pinnipeds' flippers have developed and curved to help them swim in the water and haul out on land

As pinnipeds have evolved, their flippers have become more curved and their fingers have become more spread out for more grip on land when they haul out

The walrus, Odebenids, also has more of a curved front head/jaw because of its tusks

They uses their tusks for hauling their bodies out on land, hunting, and defense unlike the eared seal and earless seal

Pinnipeds also have similar shaped femur bones which they use for mobility of the flippers and stability while on land/when hauling out for breeding, nursing their young, or hunting

http://palaeo.gly.bris.ac.uk/Palaeofiles/Pinnipeds/evolution.html

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Location & Habitat

Grey Seals are generally found in coastal waters

They survive in a cold water habitat

They will uses their blubber to keep warm

They occupy rocky coasts, islands, sandbars, ice shelves, and icebergs

Grey seals are located in the Western North Atlantic Stock

Located in eastern Canada and eastern US

They are also located in the Eastern North Atlantic Stock

Located in Britain, Iceland, Norway, Denmark, Faroe Islands, and the Russian Baltic Sea Stock

Largest native mammal in the British Isles

Physical Characteristics

Grey seal pups are born with white fur

Females have a grayish silver fur coat with some dark spots

Males have a dark grey coat with silver grey spots

Their coats are very dense coats that end at their flippers

Males also have an arched long nose, unlike females

They have a stocky, small body and females have a short snout

They weigh 130-600 lbs

Males weigh more than females

These seals are 5-7 ft long

Males are also longer than females

Males can grow to 7 ft long and weigh 600 lbs

Male grey seals also have longer necks, shoulders, and chest than female grey seals

Their hind flippers are also one-fourth of their body weight

Grey seals are also eared seals

Behavioral Characteristics

Grey seals gather into large groups for breeding and to care for their pups

They also gather in large groups to rest on land

Males and females do not eat during their 4-6 week breeding period

They use their fat from their blubber for nutrition

Males who spend more time chasing females on land have a better chance of mating

Males also compete with other males seals for access to females

Grey seals usually dive alone or in small groups when they are finding food

http://animaldiversity.org/accounts/Halichoerus_grypus/

https://animalcorner.co.uk/animals/grey-seal/

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Location & Habitat

Northern Fur Seals in the open ocean where they frequently search for beaches to reproduce

They are rarely seen on the mainland unless they are sick or breeding

Adult fur seals spend over 300 days a year foraging (searching for beaches to reproduce)

There are large groups of fur seals located on seamounts, canyons valleys, and on the continental shelf break

There is a high availability of prey in the continental shelf

The North Pacific Transition Zone is an important region for reproduction

Seals haul out on broad sandy beaches

Physical Characteristics

Northern Fur Seals have a very wide range of weight

They range from 120-600 lbs

Males weigh 300-650 lbs

Females weigh 90-110 lbs

They are typically 5-7 ft long

Male fur seals fur color is grey or black

Female fur seals fur color is light grey on their back and reddish brown on their chest with a light patch

Fur seals have a stocky body, small head, a and short snout

They have very dense fur

The cold water from the ocean does not touch their skin which preserves their body heat

But their fur is not waterproof

They have large hairless flippers which also keep them cool

Fur seals rotate their flippers forward so they can walk, run, and climb out of the water when they need to

Behavioral Characteristics

Northern Fur Seals are usually found feeding on squid, anchovy, herring, walleye pollock, and hake in the open ocean

They are not deep divers and do not go deep into the water to find their food

Since they are found in the open ocean they do not haul out on land, like walruses, to rest

They also "jug handle"

Fur seals keep their rear flippers out of the water while bobbing on the surface of the ocean

Males also have an early breeding season which starts in May

https://www.seals-world.com/seal-social-structure/
http://www.nmfs.noaa.gov/pr/species/mammals/seals/northern-fur-seal.html

http://www.marinemammalcenter.org/education/marine-mammal-information/pinnipeds/northern-fur-seal/

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Location & Habitat

Pacific Walruses live where the temperature is 5-41 degrees F

They are found where the water is 262 ft deep

Two-thirds of a walrus's life is spent in the water

Spend the summer floating on ice

They have adapted to living in a habitat of sea ice and snow

Walrus's come onto shore when the water in their habitat is too deep

Physical Characteristics

Male walrus weight- 1,764 to 3,748 lbs, 9 to 12 ft long

Female walrus weight- 882 to 2,756 lbs, 7.5 to 10 ft long

Walruses have a spindle shaped body

Cinnamon brown body color

Appear pale underwater

Calves at birth are light brown (almost grey) but become browner as they grow and their bodies develop

Their limbs are adapted as flippers; flippers are hairless

The skin on the flippers is rough and thick which provides traction on land

Each of the walrus's flippers have 5 digits all equal in length

Each digit has a claw

Behavioral Characteristics

Walrus tusks are used as weapons

A walrus can achieve dominance over another walrus by the tusk size and the aggressivness displayed

Males will fight each other and usually results in physical injuries

Walruses are very social

They are one of the most social animals

Males and females are in separate herds

Male walruses make a sound similar to a bell to display courtship to attract other women

They also haul out on land/ice to rest and care for their young

They uses their tusks to do this

https://seaworld.org/en/animal-info/animal-infobooks/walrus/reproduction
https://www.worldwildlife.org/magazine/issues/summer-2017/articles/walrus-habitat-on-the-edge

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1. Pacific Walrus
2. Northern Fur Seal (Eared)
3.Grey Seal (Earless)

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Internal/External

1.  All have four webbed flippers used to propel their bodies

2.  All have canine teeth and molars that are used to consume their prey

3.  All have large eyes and well developed whiskers for finding food in dim water

4.  All of their tails are small which limits their drag

Behavioral

1. Pinnipeds mate and can give birth on land, ice, or in shallow water and nurse their young on land. Most females usually do not eat when nursing and live off of their fat and blubber

2. Adult male pinnipeds compete with each other when mating and these competitions can result in physical scars/harm

3. Pinnipeds have strong navigational capabilities

4. When feeding, they can eat any type of food they can find in the water such as squid, octopus, and shellfish. Their flippers are used to get around in the water while feeding and to navigate

Habitat

1. Pinnipeds are found in aquatic habitats such as the open ocean, costal waters, and freshwater lakes and rivers.

2. They also haul out on land to reproduce, mate, and some nurse their young on land

3. Pinnipeds usually haul out on sandy beaches, pebble beaches, rocky shores, and tide pools

4. They travel offshore to feed off of oceanic islands

https://seagrant.uaf.edu/marine-ed/mm/fieldguide/pinnipeds.html

https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/pinniped
http://www.marinemammalcenter.org/education/marine-mammal-information/pinnipeds/

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Order Pinnipedia