Whether animals mate once or multiple times is a complex question that depends on the species. Some animals are monogamous and mate for life. Others are polygamous or promiscuous, mating with multiple partners. In some cases, it also depends on the circumstances and availability of mates.
Monogamous mating
Some animals practice monogamy, meaning they mate with one partner at a time. Swans, gibbons, French angel fish, bald eagles, and wolves are a few examples of monogamous species. These animals form long-term pair bonds and only reproduce with their mate.
However, monogamy exists on a spectrum. While some monogamous animals never seek other partners, others may occasionally mate outside the pair bond. Even within monogamous species, both males and females may pursue extra-pair copulations in some circumstances. So monogamy does not always mean mating just once for life.
Polygamous and promiscuous mating
Other animal species employ polygamous or promiscuous mating strategies. Polygamy involves one animal mating with multiple partners. Promiscuity also indicates mating with multiple mates, though without any long-term relationships.
Examples of polygamous species include deer, lions, gorillas, horses, and fruit flies. Males often mate with multiple females each breeding season. Promiscuous species include bonobos, chimpanzees, and macaques. Females may mate with many males, even mating multiple times a day.
In polygamous and promiscuous species, individuals seldom mate just once. Mating with multiple partners helps ensure genetic diversity in the population. It also increases the chances of passing on genes to future generations.
Mating frequency
How often animals mate varies greatly. Some species breed just once per season, while others may mate hundreds of times. Factors like reproductive cycles, lifespan, courtship behaviors, and environmental conditions all influence mating frequency.
Elephants, for example, typically breed only every 2-4 years when females enter estrous. Emperor penguins have just one mating season per year. Other species are almost constantly mating. Hamsters and rabbits can breed all year long and may have several litters annually.
Lifespan also affects how many times animals mate. Short-lived animals often mate at a higher frequency. Mayflies may have just 24 hours as adults to mate. Long-lived species like tortoises may mate every few years or less.
Mating frequency examples
| Animal | Mating Frequency |
|---|---|
| Elephants | Once every 2-4 years |
| Emperor Penguins | Once per year |
| Rabbits | Year round, multiple litters |
| Giant Tortoises | Once every few years |
| Fruit flies | Nearly continuously |
Mating systems
The mating system describes how often mating occurs and with how many partners. Some key mating systems include:
- Monogamy – Mating with one partner at a time
- Polygyny – Males mate with multiple females
- Polyandry – Females mate with multiple males
- Promiscuity – Members of both sexes mate with multiple partners
The type of mating system often depends on the relative parental investment of males and females. When parental investment is high, monogamy is more likely to evolve. Low parental investment tends to lead to polygamous or promiscuous mating systems.
Environmental influences
Environmental factors like climate, population density, and sex ratios also impact mating behavior. When population density is high, males and females encounter more potential mates, increasing promiscuity. Unbalanced sex ratios, with substantially more males or females, can also promote polygamy and multiple mating.
Some animals are flexible in their mating strategy based on environmental conditions. Voles, for instance, are monogamous when population density is low. But they become polygamous when densities rise and more partners are available.
Sexual selection
Sexual selection, in the form of mate choice or competition for mates, influences how often animals mate as well. In some cases, the selective pressures lead to monogamy. For example, when biparental care is critical, females may choose loyal mates. In other cases, sexual selection drives multiple mating. Males may compete intensely for access to as many females as possible.
Sexual selection can also lead to strange adaptations related to mating. Some animals evolved spike-covered penises, toxic semen, or sperm plugs to increase their paternity. So sexual selection is a key driver of animal mating behaviors and frequencies.
Once-in-a-lifetime mating
While most animals mate more than once, some extreme examples do mate just once before dying:
- Male mantises often lose their heads and lives while mating.
- Male octopuses die shortly after mating due to senescence.
- Male salmon die immediately after spawning and fertilizing eggs.
- Male spiders are sometimes eaten by the female after or during mating.
- Some animals like bamboo can reproduce just once before dying.
In species where mating is deadly, males often evolve adaptations to increase their chances of successful reproduction. For instance, male spiders may use mating plugs or dangerous stingers to stop females from eating them too soon.
Why multiple mating evolved
For most animals, mating just once is an evolutionary dead-end. Multiple mating evolved for several key reasons:
- Increased genetic diversity – Mixing genes from multiple parents ensures variability.
- Increased number of offspring – Mating multiple times allows more offspring.
- Increased chance of fertilization – More matings means more sperm and egg interactions.
- Access to resources – Females may mate with multiple males to gain access to food and shelter.
Additionally, sperm competition and cryptic female choice may drive multiple mating. When females mate with different males, it triggers competition between the sperm. This intensifies selection for the highest quality sperm.
Disadvantages of multiple mating
While multiple mating has clear evolutionary advantages, it also has some drawbacks:
- Higher risk of disease transmission from multiple partners
- Greater exposure to predators during courtship displays
- Increased energy expenditure mating rather than surviving
- Potential loss of paternal care if fathers are uncertain of maternity
For some species, the costs of multiple mating outweigh the benefits. Monogamy evolves in these cases. However, most animals employ some degree of multiple mating during their lives.
Mammalian mating systems
Mammals display the full range of mating systems. Some key examples:
- Monogamy – Beavers, gibbons, California mice
- Polygyny – Lions, elephant seals, gorillas
- Promiscuity – Bonobos, chimpanzees, macaques
In mammals, mating strategies often correlate with sexual dimorphism. Species where males control harems, like elephant seals, exhibit extreme size differences between the sexes. Monogamous species like gibbons show little dimorphism.
Social structure also influences mammalian mating frequency. Solitary mammals tend to be promiscuous. Gregarious species are more likely to be polygamous or monogamous, depending on factors like female dispersion.
Mammalian mating frequency
| Species | Mating System | Mating Frequency |
|---|---|---|
| Gibbons | Monogamy | Once per 1-3 years |
| Lions | Polygyny | Year round with multiple females |
| Elephant seals | Polygyny | Once per year with multiple females |
| Bonobos | Promiscuity | Multiple times daily with multiple partners |
Bird mating habits
Birds display some of the most variable mating systems in the animal kingdom. Most species are socially monogamous, with long-term pair bonds. However, many also engage in extra-pair copulations resulting in quasi-promiscuity.
Some examples of bird mating patterns include:
- Swans – long-term monogamy, mate for life
- Bald eagles – seasonal monogamy, new partner each year
- Albatrosses – mostly monogamous with occasional promiscuity
- Grouse – polygynous mating systems
- Ostriches – polyandrous mating by females
The extreme variation in birds reflects adaptations to different environmental and social conditions. Monogamy is common when biparental care is essential. But extra-pair mating provides the benefits of genetic diversity.
Bird mating frequency
| Species | Mating System | Mating Frequency |
|---|---|---|
| Mute swan | Monogamy | Once per year |
| Golden eagle | Monogamy with occasional promiscuity | Once per year |
| Ruff (male) | Polygyny | Daily with multiple females during breeding season |
Reptile and amphibian mating
Most reptiles and amphibians are promiscuous, though some exceptions exist. Due to their biology, mating is often seasonal:
- Many temperate species breed only in spring/summer.
- Tropical species may breed year-round or seasonally with monsoons.
- Male reptiles and amphibians provide little if any paternal care.
- Certain tropical frogs are monogamous while most are promiscuous.
Reptiles and amphibians use various strategies during the breeding season to increase reproductive success. Males fight over access to females and use display structures, pheromones, and acoustic signals to attract mates.
Reptile/amphibian mating frequency
| Species | Mating System | Mating Frequency |
|---|---|---|
| Garter snake | Promiscuity | Daily during breeding season |
| Leatherback sea turtle | Promiscuity | Several times per season every 2-3 years |
| Strawberry poison frog | Monogamy | Daily during breeding season |
Insect and arachnid mating habits
Most insects and arachnids demonstrate promiscuous mating behavior:
- Female beetles, spiders, and scorpions often consume the male after mating.
- Butterflies and dragonflies form swarming mating aggregations.
- Bees rely on polyandrous queen bees mating with multiple males.
- Female mosquitoes, however, largely mate just once, while males may mate multiple times.
Insects and arachnids often utilize bizarre sexual adaptations and strategies compared to larger animals. Due to their small size and limited mobility, aggregations and chemical signaling play key roles in finding mates.
Insect/arachnid mating frequency
| Species | Mating System | Mating Frequency |
|---|---|---|
| Orb-web spider | Promiscuity | Once per lifetime |
| Honey bee queen | Polyandry | Once every few years with multiple males |
| Monarch butterfly | Promiscuity | Multiple times during migration/breeding season |
Fish mating habits
Most fish are promiscuous broadcast spawners, releasing eggs and sperm into the water. But some exceptions exist:
- Seahorses are monogamous, with enduring pair bonds.
- Some fish are polygamous like the mating aggregations of groupers.
- Certain cichlids exhibit polyandrous mating systems.
The mating system and frequency often relate to the degree of parental care. Species where males guard eggs, like seahorses, tend toward monogamy. Those without parental care, like most bony fish, are promiscuous with no enduring bonds.
Fish mating frequency examples
| Species | Mating System | Mating Frequency |
|---|---|---|
| Seahorse | Monogamy | Daily for weeks leading to birth |
| Clownfish | Polygyny | Daily with multiple females |
| Atlantic cod | Promiscuity | Once per year |
Conclusion
Whether animals mate once or multiple times depends greatly on the species and its mating system. While examples of “one and done” mating exist, most animals mate repeatedly under the right circumstances.
Multiple mating allows increased genetic diversity, more offspring, and greater chance of reproduction. These evolutionary benefits drove the prevalence of polygamous and promiscuous mating across the animal kingdom.
But monogamy does evolve when parental care by both sexes is critical. Social and environmental factors also influence mating frequency. So for most animals, mating once is rarely enough. Ongoing mating enhances reproductive success and continuance of the species.