How do animal relationships work?
There are two things that animals always strive after, to eat and reproduce. In some species the reproduction instinct is so strong that females starve themselves for their offspring. This is seen in Southern Right Whales that only eat 3 months of the year enabling them to give birth in warm, calm waters (for more information on Southern Right Whales read our previous post Southern Right Whales 30 September 2014). Octopuses have been seen protecting their eggs for months and dies after the eggs hatch since they don’t eat anything during that time. All animal´s species (even within the same species) will have different sexual behavior. There are two mating relationships in the animal kingdom, monogamy (one partner) or polygamy (multiple partners).
There are three types of monogamy. 1: Only have one partner all their life. 2: Will have one partner at a time (might have a new partner if the first one dies). 3: Serial monogamy (will find a new partner after death or divorce of the first spouse). “Why use monogamy when it’s genetically more beneficial to have many offspring’s?” Monogamy is used in species where the young are particularly vulnerable and benefits more from having both parents protecting them. Monogamy is common in about 90 % of all bird species while in mammals only 3% of the species are monogamous. An interesting new discovery for animals that lives in monogamous relationships is that they seem to be “cheating” on each other. When looking at the offspring’s genetics quite often there are some that have different genetics then their “father”. This seems to be beneficial for the species because different genes will survive to the next generation, with a strong couple that raises the offspring together. They use monogamy to create a strong “homes” for the next generation.
Polygamy comes from the Greek meaning marriage to many spouses. There are three types of polygamy. 1: Polygyny (one male, multiple females) e.g. Cape Fur Seals and Lions. 2: Polyandry (one female, multiple males) e.g. Southern Right Whales. 3: Polygynandry (multiple male, multiple females) e.g. Bicknell thrush. Most animals that use polygamy have sexual attributes to attract partners. 90% of all mammal species use polygynous mating structure often seen as harems. In harems there will be an Alfa-male and he is the only one mating with the females. There can also be other males in the harem but they do not mate with the females. If a male challenges the Alfa-male and wins he will take over the old male harem. The new Alfa-males have different techniques to ensure that the future offspring’s in the harem will be theirs by infanticide, harassment to miscarriage or spontaneous abortion. Infanticide is when the Alfa-male kills the old male’s offspring’s to make the females get into heat again. This is used by Lions, Hippos and some monkey species. Harassment to miscarriage is used by wild horses and baboons. In some mice species males with a different scent can cause the females to spontaneously fail to implant a recently fertilized egg causing the female to abort her pregnancy.
In some species the males will care more about the first “wife”. In the European Pied flycatchers the male will leave its first “wife” when she has laid her first egg to create a second territory with a new “wife”. When the second “wife” has laid her first egg he will return to the first “wife” and care exclusively for her and her offspring.
“What is the benefit of using polygamy?” For a lot of species a large group of animals gives (harem) protection to the offspring. The dominant male also succeeds in having a lot of offspring’s in the next generation giving his genetics line a greater chance to survival.