Domestication or Co-Evolution?

Dogs have become man's best friend  accessed 23/5
http://pitvel.com/congruence-between-human-and-dogs/ 

It has long been thought that the household dog, Canis familiaris, was intentionally domesticated by humans, but there is another possibility: coevolution.

It’s been found that split between wolves and dogs may have happened up 135 000 years ago. A genetic change that long ago was most likely caused by the first relationship between wolves and humans being more of a mutual hunting strategy rather than the one sided use of wolves. About 150 000 years ago, a new, superior species of hominid outcompeted the Neanderthals. Then the first homo sapiens evolved about 80 000 years ago. These homo sapiens survived the ice age by preying on deer and mammoths and living in the caves of Spain and France.

The first canids were quite small and lived in North America when the ungulates such as horses and antelope dominated. Larger canid predators evolved quickly and spread into Asia, Europe, Africa and the rest of North America. The Canis genus was suspected to have evolved in Asia, with today grey wolf, Canis lupus, evolving around 1 million years ago. Towards the end of the ice age wolves were constantly scavenging from human kills and so the mutualism began. The humans started feeding the wolves in return for loyal companionship and help hunting.

The strong social structure of the wolf allowed it to work successfully hunting due to their knowledge of each other’s position in the hunt. This social level made the wolves extremely valuable to humans not just in the ice age hunts, but in years so come such as working together to pull sleds. This awareness is still very evident in todays “domesticated” dogs, with man’s best friend knowing who in the family is who.

These examples show that the domestication of dogs is more of a mutual co-evolution where both parties have benefited out of the relationship. From previous days of hunting to today’s times of company and protection.  

References:

W. M. Schleidt, M. D. Shalter, 2003, Co-evolution of Humans and Canids: An Alternative View of Dog Domestication: Homo Homini Lupus, Evolution and Cognition, vol. 9, No. 1, pages 57-72 

Camouflage and Identification: Canid Colouration

Canid species vary in colouration and camouflage techniques depending on habitat and identification purposes. One of the most extreme examples of this is the African Wild Dog (Lycaon pictus), (Creel & Creel, 2002).  Lycaon pictus translates to painted wolf, which refers to the extreme colouration of the animals (Creel & Creel, 2002). This patterning creates amazing camouflage and has been said to resemble "a furred version of combat fatigues" by Angier (1996). The variation in colour is generally on the body and legs of the dogs with most facial colouring being extremely similar (Creel & Creel, 2002). The three main colours are brown, black and white with a small amount of variation in the shades (Creel & Creel, 2002). Some dogs contain no white at all while others have distinct white marks on the tail and underside just behind the forelegs (Creel & Creel, 2002). Body colouration is so varied and unsymmetrical on both sides that photos of the left side of a dog cannot be connected to photos of the right side of the same dog (Creel & Creel, 2002).

Colour variation among African Wild Dogs
http://www.monartozoo.com.au/animals/african-wild-dogs/
accessed 10/5/16

The Wild dog's pattern and colouration is so distinct between individuals the dogs have been known to identify each other up to 100m away (Creel & Creel, 2002). This has been seen in interactions between separate packs in which chases have been initiated and never were members of the same pack harassed (Creel & Creel, 2002). Olfactory sense possibly works with visual identification in this instance (Creel & Creel, 2002).

In the case of the dingo (Canis lupus dingo) colouration is mainly a camouflage evolution rather than identification (Appleby et al. 2015). The main colourations such as ginger, black and tan and white help the animals blend into their surroundings (Appleby et al. 2015). Ginger animals are generally found in sandy conditions such as Fraser Island and Central Australia (Appleby et al. 2015). The black and tan colouration helps in more heavily vegetated areas such as rainforests and light colouration is best suited to either light sands or high altitude snow areas of Southern Australia (Appleby et al. 2015).

Colour variation among dingoes from different areas
http://jennyleeparker3.wix.com/aussie-canis-dingo#!blogger/c12nl accessed 10/5/16

References:

Appleby. R, Johnson. C, Morrant. D, Savolainen. P, Watson. L, 2015, The Dingo Debate: Origins, Behaviour and Conservation, CSIRO Publishing, Victoria Australia

Creel.S, Creel. N.M, 2002, The African Wild Dog: Behaviour, Ecology and Conservation, Princeton University Press, Princeton University New Jersey USA

Vocal Communications

Vocal communication among canid species varies greatly, especially between the different social structures (Cohen & Fox, 1975). Its been found from experiments on many different species including wolves, African wild dogs, foxes, coyotes, singing dogs and dingoes, that there are 12 various sounds (Cohen & Fox, 1975). These are whines, yips, hows, growls, clicks, yelps, screams, barks, coughs, coos, mews and grunts. Depending on species, these sounds may vary in time, pitch and frequency (Cohen & Fox, 1975). 66

Wolves howling
http://animaljam.wikia.com/wiki/File:Predators-forest-wolves
-howl-wolf-animals.jpg accessed 4/4

The same sound emitted by different species can mean different things. For example foxes only bark when there is a threat and scream as a greeting whereas domestic dogs bark for many reasons and growl for  a threat (Cohen & Fox, 1975). Domestic dogs are also the only species to yelp (Cohen & Fox, 1975). This is a shorter whine used for greeting (Cohen & Fox, 1975). This sound is seen to be analogous to the yip of coyotes and screams of the foxes (Cohen & Fox, 1975). Certain groups such as the Vulpines or foxes produced higher pitch sounds such as screams and were the only species to coo (Cohen & Fox, 1975). A coo is a trilly, cackle sound witch at the moment doesn't have a known meaning. The foxes also displayed minimal social sounds due to general lack of sociability (Cohen & Fox, 1975). The Canines, generally the wolves and more dog like species, produced lower sounds such as coos and guttural vocalizations (Cohen & Fox, 1975). The high pitched yipping sounds were only made by the coyotes and jackals. 129

Mixing off these sounds is used in more complicated emotional portrayal in generally the more social canids (Cohen & Fox, 1975). 'Yowling' a combination of the yelp and bark is seen in domestic dogs (Robbins, 2000). This is a social sound analogous of the wolves group howl (Robbins, 2000). Other extremely social species, such as the African wild dogs, have been known to mix many sounds creating sounds unique to them such as twitters and rumbles (Robbins, 2000). The African wild dogs also have such a range of barks that almost rivals the domesticated dogs,  thus showing the extent social structures effect vocalization variability (Robbins, 2000).

(Cohen & Fox, 1975)
Cohen. J.A, Fox. M.W, 1975, Vocalisations in wild canids and possible effects of domestication, Behavioural Processes, Vol.1(1), 77-92
Robbins. R.L. 2000, Vocal communication in free ranging Afriacn wild dog (Lycaon pictus), Behaviour, 137, 1271-1298

Canis lupus social structure

African wild dog pack
http://www.zambezitraveller.com/caprivi-kavango/
conservation/african-wild-dogs-best-team-africa accessed 2/4

Canid social structures vary for many reasons including hunting and prey size, defence and shared parenting (Macdonald, 1983). Social groups such as wolves and African wild dogs have complex social structures and use their numbers for hunting large prey (Macdonald, 1983). The Ethiopian wolf however is completely lone animal until breeding (Gotelli et al. 1994). Other Canids such as red foxes (Vulpis vulpis) have been known to live in small groups up to about five, but hunt alone (Macdonald, 1983).

Grey wolves (Canis lupus) are the largest wild canids (Mech, 1974) and tend to form packs of about 8 members, although larger packs near 40 members have been reported (Mech, 1974). The packs are comprised of mostly yearlings with a smaller amount of pups and a couple of mature adults (Mech, 1974). The packs have a dominance structure with the alpha male then female being the top (Mech, 1974). Other mature wolves in the packs are ranked separately in males and females with the higher level females protecting and feeding the pups (Mech, 1974). Greetings between dominant and less dominant wolves shows the less dominant wolf’s submissive behaviour (Mech, 1974). Active submission is portrayed by lowering the body and drawing back the lips and pushing the tongue out (Mech, 1974). Passive submission has the animal lay on its back with limbs tucked in and urinates (Mech, 1974). This behaviour is learned while pups when the pup lays on its back and the mother licks the perineal area encouraging the pup to urinate (Mech, 1974). Dominance is generally asserted while pups with the first serious position fights being at around 30 days old. These are the main dominance struggles with no more being until adulthood (Mech, 1974).

Canis lupus submissive behaviour
http://www.agefotostock.com/age/en/Stock-Images/Rights-Managed/PLP-120715p230  accessed 2/4 

Unlike most mammals, social canids such as wolves are mainly monogamous (Macdonald, 1983). The strong bonds between the alpha pair are initiated during courtship which can be up to two months before breeding (Mech, 1974). These bonds are the basis for the pack and hold the whole social structure together (Mech, 1974).

References: 

Macdonal. D. W. 1983, The Ecology of Carnivore Social Behaviour, Nature, vol. 301

Mech. L. D. 1974, Mammalian Species No. 37, Canis Lupus, The American society of Mammalogists    

Gotelli. D, Sillero-Zubiri. C, et al. 1994, Molecular Genetics of the most endangered canid: The Ethiopian wolf/ Canis simensis, Molecular Ecology, vol.3 p 301-312.

Forelimb structure and hunting

The relation between forelimb structure and hunting methods

The brachioradialis muscle is responsible for the turning out ability (supinate) in the forelimbs of most Carnivora (Souza et al. 2015). Due to the hunting tactics of running after prey, species of the Canidae family have minimal muscle with some having completely lost it (Biben, 1983).  

Feline forelimb structure showing the placement of the Brachiordialis
muscle, responsible for the supinating forelimb ability

https://www.studyblue.com/notes/note/n/cat-muscles-for-

quiz/deck/12882676

Early canids from the families Borophaginae and Hesperocyoninae had morphologies suggesting they were solitary hunters (Andersson, 2005). They had much shorter faces with larger front teeth and smaller back teeth. They were also able to turnout their forarms unlike today’s canids (Andersson, 2005). This was possible by having a large brachioradialis muscle near the elbow. These traits are similar to that of current Felidae which are predominantly lone hunters and solitary animals (Andersson, 2005). The Dingo (Canis Lupus dingo) however, has similar forelimb flexibility to the early canids with full movement in the wrists and the ability to open the forelimbs wide from the shoulder. This movement allows the dingo to withstand grappling with its prey, but also climb trees to low heights (Revil, 2013). This lets the dingo to hunt alone and be a solitary animal until mating season (Revil, 2013).  It is unknown however, whether the dingo’s morphology was retained through ancestors or re-evolved later (Revil, 2013).

Species of the Canidae family which are social and pack hunters have lost the movement in their limbs. Canids such as the bush dog (Speothos venaticus) which is highly social has evolved stiffer limb structure suited for chasing prey as a pack and having many dogs taking down the prey (Biben, 1983). Other species suited to running such as African wild dogs (Lycaon pictus) and greyhounds (Canis Familiaris) have also completely lost the brachioradialis muscle (Andersson, 2005).

Hunting techniques of the African wild dog include running after prey and attacking it as a pack.  http://voices.nationalgeographic.com/2013/11/20/top-25-photographs-from-the-wilderness-18/ accessed 22/3/16

The crab-eating fox (Cerdoeyon thous) is a smaller canid with again different social behaviour unlike the solitary dingo and packing bush dogs (Macdonald & Courtenay, 1996). The foxes stay in small groups of between two to five members (Macdonald & Courtenay, 1996). The hunting however is separate except in breeding season. The foxes contained some movement in the area of the forelimb, but again compared to other Carnivorans such as Felidae, the movement is limited (Souza et al. 2015).

References:

Andersson, K. 2005, Were there pack-hunting canids in the Tertiary, and how can we know? Paleobiology, 31(1):56-72

Biben, M. 1983. Comparative ontogeny of social behaviour in three South American canids, the maned wolf, crab-eating fox and bush dog: implications for sociality, Animal Behaviour. 31, 814-826

MACDONALD, D. W. & COURTENAY, O. 1996. Enduring social relationships in a population of crab-eating zorros, Cevdocyon thous, in Amazonian Brazil (Carnivora, Canidae). Journal of Zoology, London.  239, 329-355

Revil, R. 2013, pers. comm

Souza, P. D. Santos, L. M. R. P. Nogueira, D. M. P. Abidu-Figueiredo, M.  & Santos, A. L. Q. 2015 Occurrence and morphometrics of the brachioradialis muscle in wild carnivorans (Carnivora: Caniformia, Feliformia) Zoologia 32 (1), 23-32

  

The relationship between Jaw/skull structure and hunting strategies

Canid Skull/Jaw Structure 

Ethiopian wolf hunting small mammals
http://www.gettyimages.com.au/detail/photo/ethiopian
-wolves-searching-for-food-in-a-high-res-stock-photography/95647033
accessed 15/03 

The jaw structure varies greatly among canid species (Slater et al. 2008). Their skull shape and proportions affect bite force and speed, and prey types allowing the species to evolve and fill specific niches (Slater et al. 2008). Canids with smaller prey have evolved longer but thinner skulls allowing for fast and precise hunting (Slater et al. 2008). This enables predators such as the Ethiopian wolf (Canis simensis) to be able to catch their main prey (Ashenafi et al. 2005). The wolves half evolved to pounce and reach into the dens of small rodents which make up at least 88% of their prey (Ashenafi et al. 2005).

General hunters (Slater et al. 2008) such as the black backed jackal (Canis mesomelas) have a variety of prey. These hunters’ diet ranges from sea birds in coastal areas (Avery and Avery, 1997) to carrion, antelope and grazing stock (Grafton, 1965). The Jackals have evolved skull structures that balance strength and speed to allow them to survive in environments of natural and human influenced food sources (Grafton, 1965). The jaw structure of the Jackal is shorter and broader than that of the Ethiopian wolf, thus allowing the bones to withstand and exert more pressure.

Canids that specialise in larger prey have been proven to have very broad, short jaws (Slater et al. 2008). This evolution allows large hunters like The African wild dog (Lycaon pictus) to get the maximum amount of jaw strength (Slater et al. 2008). The dogs’ preferred prey are large animals such as gazelle and impala (Hayward et al. 2006). Due to the mass and strength of the prey, the dogs must have the jaw strength to hold the prey and be able to handle and added pressure the prey exerts (Slater et al. 2008). For this reason, the wild dogs also have larger muscle structures than the other two species mentioned (Slater et al. 2008). This adds to both pressure cushioning and added bite force (Slater et al. 2008).

Jaw structure of canids varies greatly among species. This evolution over times allows the species to fit their niches with very specific diets (Slater et al. 2008).

Figure 2. Skull structure of Ethiopian wolf (j), Black backed jackal (k) and African wild dog (i).
Slater et al. accessed  14/03

Slater, G. J. Dumont, E. R. Van Valkenburgh, B. 2008. Implications of predatory specialization for cranial from and function in canids, Journal of Zoology,

Ashenafi, Z. T. Coulson, T. Sillero-Zubiri, C. Leader-Williams, N. 2005. Behaviour and Ecology of the Ethiopian Wolf (Canis simensis) in a human dominated landscape outside protected areas, Animal Conservation 8, 113–121  

AVERY, G. AVER, D. M. 1987. Prey of coastal black-backed jackal Canis mesomelas (Mammalia: Canidae) in the Skeleton Coast Park, Namibia, Journal of Zoology London. 213, 81-94

Grafton, R. N. 1965. Food of the Black-Backed Jackal: A Preliminary Report, Zoologica Africana, 1:1, 41-53,

Hayward, M.W. Obrien, J. Hofmeyr, M. Kerley, G. I. H. 2006. Prey Preferences of the African Wild Dog Lycaon pictus (Canidae: Carnivora): Ecological Requirements for Conservation. Journal of Mammalogy, 87(6):1122–1131

Canids

Canids

Canids (Canidae) are dog like creatures including wolves, jackals, coyotes, foxes, wild dogs, dingoes and dholes with a total of 13 genera and 36 species extant. They belong to the order Carnivora, placental mammals with a diet almost entirely meat (Macdonald, Zubiri. 2004). Due to their diet, Carnivora is distinguished by the possession of carnassial teeth, used to slice their prey’s flesh (Jensen, 2007). Canidae has two subfamilies being vulpini which includes the foxes and canini which includes wolves, jackals, coyotes, dholes, wild dogs and dingoes.

Figure 1, Dog skull showing predominant Carnassial teeth.
https://en.wikibooks.org/wiki/Anatomy_and_Physiology_of_Animals/The_Skeleton
accessed 9/3/2016 

Canids are from the suborder Caniformia in which there are two superfamilies Cynoidea and Arctoidea (Macdonald, Zubiri. 2004, Jensen, 2007). Canids belong to Cynoidea while Arctoidea includes Ursidae (bears), Pinnipedea (walrus) and Musteloidea (skunks, racoons and otters) (Macdonald, Zubiri. 2004). Today’s canids share a common ancestor from over 40 MYA (Jensen, 2007). Due to this common ancestor, canids share a couple of distinguishing features which have been seen in fossils of even the extinct species (Macdonald, Zubiri. 2004). One of these features is the middle ear structure which can be used to identify between other carnivore families (Jensen, 2007).

The canids inner ear has a large entotympanic bulla (large round bone which holds ear drum) and a septum between the inner ear bones. Canids have also completely lost the stapedial artery, which connects inner ear muscles in fetuses of other mammals (Macdonald, Zubiri. 2004, Jensen, 2007, Fisher, Unknown). The placement of the carotid arteries is also different to other mammals being closer to the brain (Macdonald, Zubiri. 2004, Jensen, 2007). This placement is said to lower the risk of congestion and add protection to the arteries during the hunt (Fisher, Unknown).

Figure 2. Carnivora Family Tree
http://sweetpics.site/f/felidae-family-tree.html
accessed 9/3/16

The original “canids” belonged to the subfamily Hesperocyoninae about 40MYA. This subfamily paved the way for two more subfamilies, Borophaginae and Caninae (Macdonald, Zubiri. 2004). At this stage the dentition began to evolve (Macdonald et al, 2004) which will be mentioned more in weeks to come. The extinction of the Borophaginae subfamily allowed the caninae to populate much of North America (Macdonald, Zubiri. 2004). Leptocyon was the first species of the Caninae (Macdonald et al, 2004). This species was small with an elongated jaw and extremely similar dentition to today’s canids (Macdonald et al, 2004). The Vulpini came about later and began evolving to fit the niches the Canini had left open (Macdonald et al, 2004).  The Canids spread across Europe and Africa, then with the help of humans moved into Australia becoming the world’s largest and most spread group of predators (Macdonald, Zubiri. 2004). 

References:

David W. Macdonald, Claudio Sillero-Zubiri, 2004, The Biology and Conservation of Wild Canids, Oxford

Per Jensen, 2007, The Behavioural Biology of Dogs, CABI

A.G Timbrell Fisher, A Case of Complete Absence of Both Internal Carotid Arteries, With a Preliminary Note on the Developmental History of the Stapedial Artery, Demonstrator of Anatomy and of Surgical Anatomy, P 38-46

David W. Macdonald, Claudio Sillero-Zubiri, Michael Hoffman, Status Survey and Conservation Action Plan, Canids: Foxes, Wolves, Jackals and Dogs, 2004, The World Conservation Union