The Butterfly milkweed (Asclepias tuberose) has a unique pollination mechanism in which the plant relies on butterflies, moths, bees, ants and wasps for pollination. Hundreds of pollen grains are packaged into two connected sacs or pollinia, collectively referred to as the pollinarium. When the foraging insect lands on a flower, the pollinarium can easily attach itself to its leg. Once removed from the flower. Upon landing on another flower the pollinarium is deposited into a receptive stigmatic groove.
The Milkweed's flowers vary from white, light purple through to the intense orange of the picture above. This appeals to the insects it wishes to attract, for example butterfly's are sensitive to UV, violet, blue, green, and red wavelength peaks.
The groove's the milkweed's petals are designed so that a visiting butterfly's legs collect the pollen and to collect the pollen from other plants.
The Milkweed's flowers vary from white, light purple through to the intense orange of the picture above. This appeals to the insects it wishes to attract, for example butterfly's are sensitive to UV, violet, blue, green, and red wavelength peaks.
The groove's the milkweed's petals are designed so that a visiting butterfly's legs collect the pollen and to collect the pollen from other plants.
The milkweed seeds are produced in pods, which when open there are hundred of 'parachute' seeds inside. The silky fluff covering each seed is used to help carry it in the wind currents so that the offspring do not compete with the parental plant. This mode of dispersal is extremely effective as milkweed is considered a weed in urbanised areas, which demonstrates the vast distances the seeds can travel and their resilience to harsh climates.
The female Arrow-Shaped Micrathena Spider produces egg sacks containing about 90 eggs. The female spider carries this egg sac on her back, which is a low level of parental care.
The spider only lives for a year so it experiences only one cycle of reproduction. The level of care for young is minimal and the large quantity of young suggests r-selection is the strategy employed by the species. An advantage of this strategy is with the short lifespan of the parent the parental care is minimal regardless, have a high number of offspring increases the chance of at least one surviving. The downside is the high mortality rate, a large portion of the offspring will presumably die as they have minimal care. Also, the surviving few from r selection will have no opportunity to learn skills from their parents, so skills are either innate or learned through trial and error.
The spider only lives for a year so it experiences only one cycle of reproduction. The level of care for young is minimal and the large quantity of young suggests r-selection is the strategy employed by the species. An advantage of this strategy is with the short lifespan of the parent the parental care is minimal regardless, have a high number of offspring increases the chance of at least one surviving. The downside is the high mortality rate, a large portion of the offspring will presumably die as they have minimal care. Also, the surviving few from r selection will have no opportunity to learn skills from their parents, so skills are either innate or learned through trial and error.
Crocodiles lay hard-shelled eggs, on an average of 12–48 eggs per nest. The eggs are deposited into the nest use the sun’s heat and the natural decay of vegetation maintain a warm temperature that aids the development of the embryo. Egg incubation takes from 55 to 100 days until hatching occurs, the female usually remains close to the nest to protect the eggs from predators.
After two or three months the young are fully developed and about to hatch. After hatching the female remains close to her offspring and provides protection from predators for several weeks to months. As the young grow, they disperse, but they may remain near their nest site for over a year.
This behaviour sits in the middle of k and r-selection spectrum. The parental care is most commonly seen in k-selection, yet in the potential of having upwards of 40 offspring lends itself to r-selction criteria. This system has the advantage of multiple offspring so high mortality rates would prevent the species from dying out completely. Yet the parental care allows the young to be protected from predators and also the parental figure may provide food for the offspring. The disadvantage is that high mortality rates would still severely effect between 12 and 48 potential offspring, a larger number of offspring would benefit the chances of at least one surviving. The parental care also requires a large effort from the parent, this is potentially wasted for the inevitable death of some offspring.
After two or three months the young are fully developed and about to hatch. After hatching the female remains close to her offspring and provides protection from predators for several weeks to months. As the young grow, they disperse, but they may remain near their nest site for over a year.
This behaviour sits in the middle of k and r-selection spectrum. The parental care is most commonly seen in k-selection, yet in the potential of having upwards of 40 offspring lends itself to r-selction criteria. This system has the advantage of multiple offspring so high mortality rates would prevent the species from dying out completely. Yet the parental care allows the young to be protected from predators and also the parental figure may provide food for the offspring. The disadvantage is that high mortality rates would still severely effect between 12 and 48 potential offspring, a larger number of offspring would benefit the chances of at least one surviving. The parental care also requires a large effort from the parent, this is potentially wasted for the inevitable death of some offspring.
Cheetah's give birth to around three cubs at a time. In the first few weeks, she moves the cubs from den to den, hiding them while she is out hunting. During this time they are very vulnerable to predators such as large eagles, lions, hyenas, and baboons. Young have thick yellow-gray coat on their backs called a mantle. The mantle protects the cub from the sun and rain and helps camouflage. The mantle starts disappearing when the cub is around three months old and thins to a mane at around two years of age. Despite these protections, cub mortality rate is high, at around 90%.
The cubs that survive start following their mother at around 6 weeks of age. After a year and a half, their mother leaves them to breed again. The cubs stay together until the females reach sexual maturity at around two years of age. At that point, other male cheetahs chase the male cubs off. But the male offspring often stay together for life, forming a group called a coalition. Coalitions are beneficial because they help male cheetahs gain territory.
This breeding cycle is an example of K-selection as it shows a mother birthing to a limited number of offspring, in this case 3. Cheetah's also provides care for their offspring to reduce mortality, even though it is extremely high. The advantage of this type of reproductive strategy is that parental care is better utilised as 3 cubs get priority of their mother's care, compared to species such as crocodiles (see above). The disadvantage is that all the cubs have a chance of not making it to full maturity so their death's are significant to the mother and her chances of carrying on her genes.
The cubs that survive start following their mother at around 6 weeks of age. After a year and a half, their mother leaves them to breed again. The cubs stay together until the females reach sexual maturity at around two years of age. At that point, other male cheetahs chase the male cubs off. But the male offspring often stay together for life, forming a group called a coalition. Coalitions are beneficial because they help male cheetahs gain territory.
This breeding cycle is an example of K-selection as it shows a mother birthing to a limited number of offspring, in this case 3. Cheetah's also provides care for their offspring to reduce mortality, even though it is extremely high. The advantage of this type of reproductive strategy is that parental care is better utilised as 3 cubs get priority of their mother's care, compared to species such as crocodiles (see above). The disadvantage is that all the cubs have a chance of not making it to full maturity so their death's are significant to the mother and her chances of carrying on her genes.
Zebra's experience male and female gender roles and reproduce sexually approximately once every two years. The female Zebra moves between male's territories and as such lives a polygamous life. However, mare's have been known to stay in one Zebra's territory in a monogamous mating system. A zebra has an average of young offspring at a time, this is a system of K-selection. An embryo takes approximately a 13 month gestation period. In this period the embryo develops and grows, an example of this can be seen in the Zebra stripe's forming. In it's embryonic state it develops its first stripe markings at four weeks. These stripes face many deformations between first appearing and when the foal is birthed, yet it can be an indicator of the development. A larger embryo will result in more stripes on a mature Zebra ( more here ).
A zebra foal will stay with its mother for some time nursing heavily from their mother for up to 6 months. It could take as long as three years to be completely weaned. At around 3 years of age females reach sexual maturity, for males it is around 6 years of age. The parental care is dependent on the mother, the father is not involved.
A zebra foal will stay with its mother for some time nursing heavily from their mother for up to 6 months. It could take as long as three years to be completely weaned. At around 3 years of age females reach sexual maturity, for males it is around 6 years of age. The parental care is dependent on the mother, the father is not involved.