What is a species?What is a species?

A group of organisms A group of organisms so similar to one so similar to one another that they another that they can can

breedbreed and and produce produce fertile offspring.fertile offspring.

In plants, the pollen must be able to “match perfectly” shape-wise to the stigma of the female part of the flower.If the match occurs, then the pollen digests a tube to the eggs below. Fertilization can take place.

Pansy pollen doesn’t match yucca stigmas.

Sunflower pollen doesn’t match rose stigmas.

In animals, the tip of the sperm In animals, the tip of the sperm must match (shape-wise) to must match (shape-wise) to the egg’s covering.the egg’s covering.

One protein on the tip of the sperm

One protein on the covering of the egg.

If the shape of the proteins don’t match, then no baby is made.

If the sperm (red proteinred protein) from a sea turtle isput on the egg (brown brown proteinprotein) of a snapping turtle, fertilization doesn’ttake place.

Snapping turtles are adifferent species than sea turtles.

Sometimes the proteins of two species gametes are very close in shape and size.

Cow protein on eggBuffalo protein on egg

30 chromosomes30 chromosomesMale bullMale bull

30 chromosomes30 chromosomesFemale buffaloFemale buffalo

30 chromosomes30 chromosomesBeefalo Beefalo

fertility, fertility, milking ability, milking ability, and ease of handlingand ease of handling

hardinesshardiness, , foraging abilityforaging ability, , calving easecalving ease, , and and meat qualitymeat quality

The egg’s The egg’s protein of a protein of a horse horse matches matches the sperm’s protein of a the sperm’s protein of a donkeydonkey. . MuleMule

Donkeys have 62 chromosomes

Horses have 64 chromosomes

Mules have 63 chromosomes that are a mixture of one from each parent.

The chromosomes don’t pair up properly during meiosis, so sex cells are rarely made in mules.

Though very uncommon, some fertile mules do exist.

Mule

Are Ligers a species?Are Ligers a species?

Only if they can breed to produce fertile offspring.

Dogs, wolves and foxes are similar. Can they mate and produce fertile offspring?

Breeds of dogs can interbreed. Dogs are one species. Sometimes, dogs and wolves interbreed though they are not the same species.

How dogs in cold places may have all end up with long hair.

Die from being cold.