There is a world somewhere between reality and fiction. Although ignored by many, it is very real and so are those living in it. This forum is about the natural world. Here, wild animals will be heard and respected. The forum offers a glimpse into an unknown world as well as a room with a view on the present and the future. Anyone able to speak on behalf of those living in the emerald forest and the deep blue sea is invited to join.
(03-07-2021, 10:11 AM)Balam Wrote: I wanted to make this post to clear up some misconceptions I've seen spread regarding the sexual dimorphism on jaguars and how it compares to other felids of the genus Panthera. There is an idea I've seen that claims jaguars have the least pronounced sexual dimorphism among the pantherine felids and this somehow translates to them being the worst fighters (??). I find this claim to be, to put it mildly, ridiculous and speaks to how easy it is for people to spread misinformation about a species they dislike when the data used is skewed and the public it is being presented to might not be the most versed on the subject to push back against it.
In terms of body size, jaguars present sexual size differentiations that fall in line with what is seen with other pantherine cats, with males being usually 30% larger than females, while the largest individuals of each sex having a very drastic sexual demarcation, with the heaviest male being almost 50% larger than the heaviest female on record (100-110 kg vs 148 kg, Troncha/Lopez). Sexual size differences and therefore dimorphism also varies across different jaguars populations, as described by Hoogestijn and Mondolfi in their paper BODY MASS AND SKULL MEASUREMENTS IN FOUR JAGUAR POPULATIONS AND OBSERVATIONS ON THEIR PREY BASE (1996). Here, by comparing the size differences among the two largest populations, Llanos and Pantanal, it became clear that Llanos jaguars showed more pronounced size differences among the sexes:
*This image is copyright of its original author
*This image is copyright of its original author
The aspect ratio in weight differences between Llanos jaguars was 1.1:0.67, for Pantanal jaguars it was 1:0.77. In the Llanos, according to this study, the females were 36%, whereas in the Pantanal the gap between the sexes was 23%. By contrast, if we compare these ratios to Persian leopards, as an example, from Patterns of sexual dimorphism in the Persian Leopard (Panthera pardus saxicolor) and implications for sex differentiation by Farhadinia et al. we get the following:
*This image is copyright of its original author
Aspect ratio 0.66:0.45, with males being roughly 32% larger than females. Therefore, jaguars from the Llanos would show an even greater gap in size than Persian leopards, while Pantanal jaguars would remain with the smaller gap size among the three populations.
These size gaps remain constant with skull measurements as well:
*This image is copyright of its original author
*This image is copyright of its original author
In skull length, the Pantanal male jaguars had a longer skull by 11,3%, whereas with Llanos jaguars the skulls of the males were longer by 16.2%.
When we compare the ratio differences between floodplain jaguars and their immediate interspecific size counterparts, the Sunda tigers, we get the following results from the tigers, using the data on the greatest skull length of Mazak and Grove from A taxonomic revision of the tigers (Panthera tigris) of Southeast Asia:
*This image is copyright of its original author
For the extant population of Sumatran tigers, male skulls were 12,51% longer than females, putting the size difference only slightly higher than Pantanal jaguars, but substantially lower than Llanos jaguars. So far, Llanos jaguars have shown the most drastic sexual dimorphism on weight craniometric measurements compared to three other populations of pantherines.
Here's 130 kg Ruxu mating with Jagua female, the size difference between these two could not be more obvious:
This discussion of marked sexual dimorphism is derived from a claim that jaguars having the least prominent secondary sexual differentiating traits somehow means that male jaguars are less equipped to fight in comparison to other pantherines, and the ones pushing for this idea focus on the dewlap in the leopard to make their points. What do actual scientists and biologists from reputable organizations have to say about the function of dewlaps in leopards? Johanna Taylor from Panthera released the following article on the subject:
"Mature male leopards are at least 60% larger than females, and broader, with larger chest girths and longer, bulkier heads. But there’s something else you may notice that sets males apart: Their thick necks can be adorned with a loose flap of skin hanging underneath. These skin folds are called dewlaps.
Dewlaps are observed in a variety of species throughout the animal kingdom, most notably in certain birds, lizards, and hoofed mammals. In mature male leopards, a well-developed dewlap is prominent and one of the best ways to determine age. However, the function of leopard dewlaps remains unknown and largely unexplored. Since they are a sexually-dimorphic feature—meaning only one sex exhibits the trait—scientists speculate that this enigmatic ornament is linked to sexual selection or male fitness.
Of another conspicuous, sexually-dimorphic feature among cats—the mane of a male lion—Charles Darwin postulated: “[It] forms a good defense against the one danger to which he is liable, namely the attacks of rival lions.” The idea behind this hypothesis is that adaptations such as body armor or weaponry, like antlers on male deer, increase the ability of males competing against other males. Most often the winner is the lucky male who gets to mate with the female and pass on his genetics.
On the other hand, results of more contemporary research indicate that injuries sustained during fights between lions don’t appear to differ between maned and non-maned sub-adult males or even females. This outcome suggests that the mane/neck area is not a high-target region during fights. Instead, observations find that the back and hindquarters seem to be the targeted areas during confrontations.
Many biologists believe that a male lion’s mane serves as an indicator of sexual fitness. Studies using life-sized toy lions sporting contrasting mane colors and lengths found that male lions were more likely to approach the imposters with lighter, shorter manes, while female lions were drawn more to models with darker manes. These results suggest that males with shorter, blonder manes are less intimidating to rival males, and thus perceived to have lower overall fitness.
We can apply this theory to hypothesize about the functions of a dewlap on a male leopard. However, fights between elusive male leopards are rarely observed and documented by scientists. This makes it difficult to confirm if the leopard’s dewlap has any defensive functions. Likewise, it’s hard to determine if it serves a similar purpose to that of a large, dark mane in sexual selection, as an indicator of fitness and longevity.
Another speculation about the dewlap is that it simply makes mature leopard males appear larger and more intimidating to rivals. Typically, as a male leopard ages, his dewlap enlarges. Mature males hold wider territories and have more opportunity to mate with females.
This also means that there are more opportunities to come into conflict with other males seeking the same territory and females. It would be ideal to avoid physical confrontation, and potential injury, by being able to display fighting capability and fitness, thus deterring potential rivals without physically engaging them. Fighting with other males has potential to lead to injury or death. Even the smallest injuries can fester and inhibit hunting abilities, leading to a decline in body condition that could result in death.
Younger and smaller males may be dissuaded from engaging in a fight with a larger male sporting a more pronounced dewlap. Alternatively, estrous females may select a male with a larger dewlap, perceiving him to have greater fitness than his peers. As of yet, no studies have been conducted to determine if dewlap size correlates with testosterone levels or is linked to reproductive success as an indicator of longevity."
The claims stated above by Dr. Taylor are very clear in that the function of the dewlap in leopards as a sort of protection for males during territorial fights has little to no scientific standing and is not widely supported by biologists and researchers. Instead, much like many other species of animals, by making the neck of the leopard appears larger, males are able to avoid direct confrontation by intimidating smaller males who might not want to risk injury in the case of a fight that could prove fatal down the line.
It is also claimed that among 4 of the 5 pantherines in this discussion the jaguar shows the lesser external dimorphic traits and that besides the dewlap in leopards and the manes in lions, male tigers have ruffs around their heads which females, according to them, do not, and therefore that trait symbolizes that tigers have more frequent confrontations than jaguars. How exactly is a short patch of hair around the jaws supposed to defend a tiger from 10 cm canines is beyond me, but that is their claim.
This is of course not true, the ruff in tigers is present in both sexes and it not always consistent in size or occurrence at all. Here's a captive Sumatran couple mating, the female just like the male possesses a large ruff of hair around her head:
Here's a wild female displaying a small ruff as well:
By contrast, the very famous Umarpani male who is renowned for defending his territory and even going as far as to kill larger opponents in fights does not have ay ruff around his head:
According to the "hypothesis" of the external sexual dimorphic traits and their link to fighting abilities, one would expect a dominant male tiger such as Umarpai to show a very marked and distinct ruff around his head, but this is not the case. The lack of ruffs around the face can also be appreciated with Sundarbans tigers, female and male for comparison:
To further expand on the interspecific fights among jaguars and how they compare with other felids, jaguars in areas where resources are scarcer such as the Cerrado have shown to be particularly aggressive with each other. Last year we documented the case of a very large melanistic male named Tiago that was killed in a territorial dispute with a different male, and his adversary managed to get a grip of his nape which allowed him to tore it apart, killing the huge 117 kg jaguar.
Jaguars in the Pantanal too have been recorded killing each other through the perforation of the skull, although in some areas jaguars may be more tolerant of each other and males may share territories in relative peace since the prey abundance of the area allows them to share resources, but this is not the universal case for jaguars.
With all of this being said, it's very clear that the idea that jaguars are somehow outliers among its cousin in terms of sexual dimorphism is a lie, there is no hard science to back up those assertions, just the conjectures of people with an agenda who need to hype up their favorite cat by spreading misinformation about another one they dislike. It's important to show hard data when participating in these discussions because otherwise the uninformed opinions of certain people may be confused for facts and quickly spread around among more easily impressionable minds.
I don't know where this statement comes from (i.e. having the least sexual dimorphism resulting in being worse fighters) nor do I believe it, but skull-wise jaguars do have the least sexual dimorphism.
Compared to females, adult male skulls from Central America were 13.2% larger, from the Amazon 10.8% larger, from the Pantanal 12.8% larger, and from the Llanos 19.3% larger:
*This image is copyright of its original author
The following tables from Pocock and Allen show skull measurements for leopards from the Congo Basin forest and the adjacent forest/savanna mosaic habitat. The average skull length for 22 adult males was 254.2mm and for 18 females 193.4mm, a difference of 31.4%.
*This image is copyright of its original author
*This image is copyright of its original author
*This image is copyright of its original author
*This image is copyright of its original author
For lions, we have average skull length for a total of 130 adult male and 126 adult female lion skulls from all over Africa, with male skulls being 21.2% larger.
*This image is copyright of its original author
From the same paper, skull lengths of Kruger lions specifically and Bengal tigers. Kruger lions show a difference of 21% while Bengal tigers show 19.8%.
*This image is copyright of its original author
Again from the same paper, skull lengths of adult tigers from Southeast Asia, both Javan and Sumatran tigers show a difference of around 15.5%.
*This image is copyright of its original author
Skull measurements of Bengal, Caspian, and Amur tigers. A difference of 18.9% for Bengal tigers, 19.2% for Caspian tigers, and 23% for Amur tigers.
*This image is copyright of its original author
I didn't mention you in this post but if the shoe fits, oh well.
Here's the quoted study that you clearly didn't read and instead opted for taking the tables without the full context, I presume from a Tapatalk forum, for lion and tiger skull length measurements Brain size of the lion (Panthera leo) and the tiger (P. tigris): Implications for intrageneric phylogeny, intraspecific differences and the effects of captivity, Yamaguchi et al.:
*This image is copyright of its original author
Wild male tigers had a skull length 17.5% larger than females, which is lesser than Llanos jaguars, wild male lions were 21.4% longer than females, only slightly above Llanos jaguar measurements in skull length only.
Lions separated into two different populations, interesting how you didn't put the Asiatic lion's skull length difference, I wonder why:
*This image is copyright of its original author
Melanochaita wild male lions had skull lengths larger consistently with the value above at 21.2%, whereas leo leo had skulls longer by 12.92%. The first population had males with skulls proportionally longer than females only 2% greater than Llanos jaguars, whereas in the second one the size difference between them and Llanos jaguars was 6.3% in favor of the jaguar, and very close to the skull size difference between Pantanal jaguars of 12.77%.
Not only did you inflate the value of Sumatran tigers, but you purposely left out Bali tigers because the size difference in skull length between them is in fact lesser than Llanos jaguars and very close to Pantanal jaguars. In fact, Llanos jaguars had the largest size difference in skull length than all the tigers on the table above.
In my post, I mentioned skull length because I didn't feel like going by each measurement in skull size which also involves skull width, which is something you always conveniently leave out. Let's go over the skull width comparisons between Sunda tigers and jaguars. Again data from A taxonomic revision of the tigers (Panthera tigris) of Southeast Asia:
Llanos jaguars had skull size differences greater than Malayan tigers and statistically equal to Javan tigers, the other jaguar populations had values lower but Pantanal and CA jaguars had values similar to Malayan tigers off by less than 2%.
For Central African leopards according to the tables you posted: males had an average skull width of 150.1 mm, females had an average skull width of 122.7 mm.
The tables you posted have the skull length of measurements of 28 adult male leopards, why did you say 22? Did you purposely discard the 5 young adult males from the sample of the Northeast Congo table? Seems like you did, do you know what this is called? Sample bias, you are ignoring the values of young adult males because they lower the average of the entire population as you're trying to inflate their value to make them seem bigger than what they truly are. Guess what? For all other felids, the age ranges used to determine average include very young to very old adults. This is no different than your attempt at trying to inflate the average weight of Natal leopard by only including the age class of prime individuals. Nice try.
The actual average for the length of leopards according to the table you posted is 244.7 mm not 254.2 for males. Therefore the size difference between both sexes is in fact 26.5% and not 31.4%.
Conclusion: the size differences in craniometric values for floodplain jaguars in fact overlap greatly with the values of lions and tigers across different populations, with the jaguars being lesser or higher depending on the population. The claim that jaguars show less sexual dimorphism in both body mass and skull size is false.
And since we're going over all this data, I'm going to take the chance to go over another myth that seems rampant online, that Central/West African leopards have wider skulls than other leopard populations and thus "compare to jaguars". I will use Guate's data compilation on Persian leopards to see how they compare to the rainforest leopards in question in terms of aspect ratio between the breadth and length of the skulls:
*This image is copyright of its original author
Persian leopards 245mm/162mm, 1.51:1
Central-West African leopards 244.7mm/150.1, 1.63:1
Therefore rainforest leopards have skulls that are about 12% longer in comparison to their width than Persian leopards. And since you like to use skull width to compare Central African leopard to jaguars to substantiate your claims that they supposedly overlap in size, then:
1) You cannot compare two species with different anatomical traits that show proportionally different measurements in different areas of their bodies to assume that one species will yield the same amount of mass as the other one based on one specific trait, such as skull length. If that was the case then lions would be significantly larger than tigers since in skull length they have proportionally longer skulls (see the Yamaguchi tables above), and yet we know this isn't true. Leopards too have proportionally longer skulls than jaguars by a long mile, so any measurement from a leopard that compares in skull length to a jaguar's skull length will mean that the leopard will be the smaller animal regardless.
2) Based on the data that you posted, rainforest leopards have skull lengths similar to Central American jaguars (244.7-243.6), but in skull width rainforest leopards actually compare to Central American female jaguars and not the males (150.1-160.2/148.7). Not only would the Central American jaguars be larger according to this data, but this also substantiates the data on weights that we do have on Central and West African leopards, from Spatial organization of leopards Panthera pardus in Taï National Park, Ivory Coast: Is rainforest habitat a ‘tropical haven’, one healthy male from Ivory Coast weighed 56 kg:
*This image is copyright of its original author
And of course, we know that two males found on a snare in Central Africa did not surpass 50 kg in weight, even if healthy they wouldn't have been much heavier.
So you can stop lying to people over at different forums about Central African leopard growing to the same size as Pantanal jaguars (I had issues writing that sentence with a straight face). Leopards also do not overlap in skull width with jaguars, another one of your lies.
Why so hostile when I just added data to support the claim that jaguars are least sexual dimorphism when it comes to the skull department whereas leopards have the highest sexual dimorphism? You tried to correct me, but in the end you failed to prove otherwise. Skull-wise they do have the least sexual dimorphism.
Yes the young adult ones were not included (what a crime right?) and no it was never the intention to inflate their value.
Quote:The actual average for the length of leopards according to the table you posted is 244.7 mm not 254.2 for males. Therefore the size difference between both sexes is in fact 26.5% and not 31.4%.
So even when you add the young adult ones the leopard still remains on top regarding sexual dimorphism.
Quote:And since we're going over all this data, I'm going to take the chance to go over another myth that seems rampant online, that Central/West African leopards have wider skulls than other leopard populations and thus "compare to jaguars". I will use Guate's data compilation on Persian leopards to see how they compare to the rainforest leopards in question in terms of aspect ratio between the breadth and length of the skulls:
And why are you bringing this up? I never said a word about this in my previous post?
Oh well, first of all I've always claimed them to be wider than other populations/subspecies bar the Persian leopard. The fact that you have to bring up said subspecies proves me right. For your information; Central African leopards have at maximums the longest skulls (+280 mm), Persian leopards the widest (191 mm).
Quote:1) You cannot compare two species with different anatomical traits that show proportionally different measurements in different areas of their bodies to assume that one species will yield the same amount of mass as the other one based on one specific trait, such as skull length. If that was the case then lions would be significantly larger than tigers since in skull length they have proportionally longer skulls (see the Yamaguchi tables above), and yet we know this isn't true. Leopards too have proportionally longer skulls than jaguars by a long mile, so any measurement from a leopard that compares in skull length to a jaguar's skull length will mean that the leopard will be the smaller animal regardless.
But leopards too overlap in skull width! I've told you this numerous times. Go back and check GuateGojira's data compilation and you'll see there are leopards with skull widths of 191 mm which is wider than the average Amazonian male jaguar, female Pantanal jaguar and only marginally narrower than the average Pantanal and Llanos male jaguar. This is the one I'm talking about, the one from the Mazandaran province.
*This image is copyright of its original author
271 mm x 191 mm or 18.19" compared to the average Amazonian male jaguar (17.26"), female Pantanal jaguar (16.93"). The average Pantanal male jaguar has a score of 19.08" and the average Llanos male 19.04". I don't know about you but that is literally called an overlapping.
Quote:2) Based on the data that you posted, rainforest leopards have skull lengths similar to Central American jaguars (244.7-243.6), but in skull width rainforest leopards actually compare to Central American female jaguars and not the males (150.1-160.2/148.7).
How hypocritical of you; you're the first to whine about different sample sizes (read: small) and yet you're keen to compare a sample of 7 to one of 28. Here's more data although we're not sure of the gender, it's however most likely males only:
*This image is copyright of its original author
Quote:Not only would the Central American jaguars be larger according to this data, but this also substantiates the data on weights that we do have on Central and West African leopards, from Spatial organization of leopards Panthera pardus in Taï National Park, Ivory Coast: Is rainforest habitat a ‘tropical haven’, one healthy male from Ivory Coast weighed 56 kg:
The discussion and the additional data posted is about Central African leopards only, you posting data of ONE West African leopard is irrelevant. That's what I call selective posting.
What's funny is that even this single West African leopard is more impressive than the following Central American jaguars because he belongs in the upper weight category and has a more impressive neck girth than any of the jaguars. But let me guess, fat dewlap?
*This image is copyright of its original author
*This image is copyright of its original author
Quote:And of course, we know that two males found on a snare in Central Africa did not surpass 50 kg in weight, even if healthy they wouldn't have been much heavier.
Those are reported weights from poachers, those animals where starving and in poor condition. Plus they already were close to 50kg so this is nonsens.
Quote:So you can stop lying to people over at different forums about Central African leopard growing to the same size as Pantanal jaguars (I had issues writing that sentence with a straight face). Leopards also do not overlap in skull width with jaguars, another one of your lies.
Trust me, you have more issues than writing something with a straight face. And first they are similar to a particular jaguar population and now all of a sudden they do not overlap? Make up your mind for once.
Comparing Cats: A Discussion of Similarities & Differences
