BOX 1. LIFE HISTORY STRATEGIES
Are carrots (Daucus carota ) similar to blue ringed octopuses
(Hapalochlaena lunulata )? They both start life small, grow fast
but few survive to adulthood, produce many offspring in one breeding
event at around 1 years old, and are semelparous . In contrast,
humans (Homo sapiens sapiens ) and blue whales (Balaenoptera
musculus ) grow slowly, mature late but are likely to survive to
adulthood, usually produce one offspring every 2-3 years and have
remarkably similar lifespans: the oldest known living human, Jeanne
Calment, reached 122 years of age, and blue whales may live up to 110
[64]. The sacred fig tree (Ficus religiosa ) and giant barrel
sponge (Xestospongia muta ) are like carrots and blue ringed
octopuses in that they start life small, are unlikely to survive to
adulthood and, once mature, produce many offspring. Xestospongia
muta and F. religiosa are also like humans and blue whales,
however, as they are iteroparous over long lifetimes: one
sacred fig “Jaya Sri Maha Bohi” in Sri Lanka is the oldest known
human-planted tree, which at around 2,300 years old is similar in age to
the oldest known Caribbean giant barrel sponge [65].
Whilst distantly-related organisms may share similar life history
strategies, closely-related organisms can show remarkably different life
histories. The Dasyuridae family, to which the Tasmanian devil
(Sarcophilus harrisii ) belongs, is one of the most diverse
marsupial families [66], with dasyurid species showing different
life history strategies, despite being closely related. Maturity occurs
at ~11 months but, while in some species all individuals
die by 12 months old following a single synchronous mating, others
reproduce many times annually and live for several years [67] .
Plant life history strategies are often even more labile than animal
strategies: pine trees (Pinus spp.) vary vastly in lifespan,
despite having similar morphology and physiology: the Virginia pine
(P. virginiana ) rarely lives over 150 years [68], whereas
bristlecone pine (P. longaeva ) hold the record of non-clonal
longevity, at 4,850 year old [69]. Selection for varying longevities
in pines may be a result of the differing fire environments [70].
The Tree of Life abounds with examples of distantly related organisms
sharing convergent life history strategies, despite divergent body size
and lifestyle, and vice versa . Evolutionary ecologists seek to
understand, across broad taxonomic groups, how and why diverse life
history strategies, such as those exemplified here, are distributed
across phylogenies, space, and time.