Temporal Isolation — Definition & Examples

What Is Temporal Isolation?

Imagine that you are a squirrelologist. You are studying two populations of squirrels that live in your backyard. There are gray squirrels and brown squirrels.

You observe that you never see gray-brown squirrels. This seems strange to you because you know that the squirrels interact a fair amount. As you study the two squirrel populations, you find out that brown squirrels only mate from April to June. However, the gray squirrels only mate from August to October.

You can now conclude with confidence that these two squirrel populations are experiencing temporal isolation.

Recall that geographic isolation depends on where populations do things. Two populations are temporally isolated because of when they do things. This could be as large a difference as mating seasons and as small a difference as what time of day they are active. Being temporally isolated makes it less likely for two populations to reproduce. This leads to speciation since the two populations are not sharing any genes.

Temporal Isolation

Isolating mechanisms prevent species from mating with one another.

Sometimes similar populations that live in one area reproduce at different times of the year. For example, one population might breed during the fall and another during the spring. The two populations cannot interbreed because of temporal isolation.

This type of isolation occurs when two populations reproduce at different times of the day or in different seasons.

Since they do not interbreed, over time they can become different species through a process called speciation.

What Is an Example?

Below is an example of two flowers in a population. The flowers grow in the same area, but one blooms and releases pollen in May while the other does not. The second flower might bloom a bit later instead.

Since the flowers do not reproduce at the same time, they cannot cross-pollinate. This means that the two groups of flowers are temporally isolated. Over time, the two groups can split off into two new species which can no longer interbreed.

Introduction to Temporal Isolation

Temporal isolation is a prezygotic barrier that leads to speciation, or the formation of new species. Other types of prezygotic barriers include geographic, reproductive, and behavioral isolation.

When two populations of one species are isolated this way, they no longer reproduce with each other due to differences in mating times.

What's Temporal Isolation?

Temporal isolation means that two parts of a population reproduce at different times. Temporal is a fancy way of saying time.

If half of a population mates in January and the other half mates in June, they straight up won't be able to breed together. The difference in mating times can be from days to years apart, so the populations eventually become separate species. This type of isolation is more popular for plants, but some animals have also experienced it.

An amazingly cute example of this is eastern and western spotted skunks. The eastern spotted skunk likes to mate in the fall, while the western spotted skunk likes to mate in the spring. Because of this time difference, they don't mate together and have become different species. Seriously, just look at that little spotted skunk. Too cute.

$$\color{#8925AE}{\text{Vocabulary Review:}}$$

$\color{#8925AE}{\text{Speciation}}$ : One species splitting into two distinct species

$\color{#8925AE}{\text{Isolating Mechanisms}}$ : Types of isolation that lead to the formation of a new species

$\color{#8925AE}{\text{Behavioral Isolation}}$ : A portion of a species undergoes a behavior change and no longer mates with the other part of the species

$\color{#8925AE}{\text{Geographic Isolation}}$ : A portion of a species becomes separated by geography and can no longer mate with the other part of the species

$\color{#8925AE}{\text{Temporal Isolation}}$ : A portion of a species changes the time they are awake or time they breed, and they can no longer mate with the other part of the species

(Video) Speciation: Of Ligers and Men

by CrashCourse

Temporal isolation is when groups of organisms become separated because they mate at different times. In this video, Crash Course discusses pre-zygotic barriers that lead to speciation.