New species pdf

The nectar-eating birds have long beaks to dip into flowers to reach the nectar. The insect-eating birds have beaks like swords, appropriate for stabbing and impaling insects. Can divergence occur if no physical barriers are in place to separate individuals who continue to live and reproduce in the same habitat?

The answer is yes. One form of sympatric speciation can begin with a serious chromosomal error during cell division. In a normal cell division event chromosomes replicate, pair up, and then separate so that each new cell has the same number of chromosomes. However, sometimes the pairs separate and the end cell product has too many or too few individual chromosomes in a condition called aneuploidy Figure Polyploidy is a condition in which a cell or organism has an extra set, or sets, of chromosomes.

Scientists have identified two main types of polyploidy that can lead to reproductive isolation of an individual in the polyploidy state.

Reproductive isolation is the inability to interbreed. In some cases, a polyploid individual will have two or more complete sets of chromosomes from its own species in a condition called autopolyploidy Figure Polyploidy results from an error in meiosis in which all of the chromosomes move into one cell instead of separating. These new gametes will be incompatible with the normal gametes produced by this plant species.

However, they could either self-pollinate or reproduce with other autopolyploid plants with gametes having the same diploid number. In this way, sympatric speciation can occur quickly by forming offspring with 4 n called a tetraploid. These individuals would immediately be able to reproduce only with those of this new kind and not those of the ancestral species.

The other form of polyploidy occurs when individuals of two different species reproduce to form a viable offspring called an allopolyploid. Figure 12 illustrates one possible way an allopolyploid can form. Notice how it takes two generations, or two reproductive acts, before the viable fertile hybrid results.

The cultivated forms of wheat, cotton, and tobacco plants are all allopolyploids. Although polyploidy occurs occasionally in animals, it takes place most commonly in plants. Animals with any of the types of chromosomal aberrations described here are unlikely to survive and produce normal offspring. Scientists have discovered more than half of all plant species studied relate back to a species that evolved through polyploidy.

With such a high rate of polyploidy in plants, some scientists hypothesize that this mechanism takes place more as an adaptation than as an error. Given enough time, the genetic and phenotypic divergence between populations will affect characters that influence reproduction: if individuals of the two populations were to be brought together, mating would be less likely, but if mating occurred, offspring would be non-viable or infertile.

Many types of diverging characters may affect the reproductive isolation , the ability to interbreed, of the two populations. Reproductive isolation can take place in a variety of ways. Scientists organize them into two groups: prezygotic barriers and postzygotic barriers. Recall that a zygote is a fertilized egg: the first cell of the development of an organism that reproduces sexually.

Therefore, a prezygotic barrier is a mechanism that blocks reproduction from taking place; this includes barriers that prevent fertilization when organisms attempt reproduction. Some types of prezygotic barriers prevent reproduction entirely.

Many organisms only reproduce at certain times of the year, often just annually. Differences in breeding schedules, called temporal isolation , can act as a form of reproductive isolation. For example, two species of frogs inhabit the same area, but one reproduces from January to March, whereas the other reproduces from March to May Figure In some cases, populations of a species move or are moved to a new habitat and take up residence in a place that no longer overlaps with the other populations of the same species.

This situation is called habitat isolation. Reproduction with the parent species ceases, and a new group exists that is now reproductively and genetically independent. For example, a cricket population that was divided after a flood could no longer interact with each other. Over time, the forces of natural selection, mutation, and genetic drift will likely result in the divergence of the two groups.

Behavioral isolation occurs when the presence or absence of a specific behavior prevents reproduction from taking place. For example, male fireflies use specific light patterns to attract females. Various species of fireflies display their lights differently. If a male of one species tried to attract the female of another, she would not recognize the light pattern and would not mate with the male. Other prezygotic barriers work when differences in their gamete cells eggs and sperm prevent fertilization from taking place; this is called a gametic barrier.

Similarly, in some cases closely related organisms try to mate, but their reproductive structures simply do not fit together. For example, damselfly males of different species have differently shaped reproductive organs. If one species tries to mate with the female of another, their body parts simply do not fit together. Figure In plants, certain structures aimed to attract one type of pollinator simultaneously prevent a different pollinator from accessing the pollen.

The tunnel through which an animal must access nectar can vary widely in length and diameter, which prevents the plant from being cross-pollinated with a different species Figure When fertilization takes place and a zygote forms, postzygotic barriers can prevent reproduction.

Hybrid individuals in many cases cannot form normally in the womb and simply do not survive past the embryonic stages.

This is called hybrid inviability because the hybrid organisms simply are not viable. In another postzygotic situation, reproduction leads to the birth and growth of a hybrid that is sterile and unable to reproduce offspring of their own; this is called hybrid sterility. For Miodon christyi, Broadley and Pitman : , Morphometric data in mm and meristic scale counts for examined specimens of Polemon christyi, P. For character abbreviations, see Materials and Methods.

See Materials and Methods for 15 7 7 1 2 abbreviations. Asterisks next to species names indicates data included from type specimens. Polemon christyi, Welch ; part : Polemon christyi, Hughes ; part : , appendix A.

Polemon christyi, Chifundera ; part : table 1. Polemon christyi, Behangana and Goodman ; part : Polemon christyi, Spawls et al. Polemon christyi, Broadley and Cotterill ; part : 47, Polemon christyi, Chirio and Ineich ; part : Polemon christyi, Caro et al.

Branch, 25 January Referred material. Loveridge, ; Caro et al. Cytochrome b grayish black or black with silver-white edging on ventral and ND4 pairwise sequence divergence rates between P. Description of the holotype. Maxillary dentition—two small anterior teeth, followed by a very large, deeply grooved fang positioned anterior to eye, followed posteriorly by 12 smaller teeth on each side.

These data are nearly identical to those reported by Tilbury and Branch Coloration of the holotype in life. The anterior forked portion of the tongue is silver white, which transitions to grayish black posteriorly. Coloration of the holotype in preservative. The paratype PEM R was a badly damaged adult female. There were no differences between the two speci- mens in terms of coloration in preservative, as both were uniform grayish black dorsally and ventrally.

The female is larger mm SVL , has fewer subcaudals 15 , and has a proportionately shorter tail 4. Ventrals were not counted for the paratype because it was badly damaged.

A Closeup of et al. Broadley and Pitman and Broadley et al. De Witte reported that a specimen from black with silver-white edging on ventral and subcaudal Upemba National Park in southeastern DRC contained one scales vs. Specimens from southeastern DRC and Zambia are scale irregular vs. Scale bars represent 2 mm. The paratype was found dead in a pit Fischer noted that P.

The new species is known to consume snakes workers. Specimens from Upemba National Park in south- that are relatively large. The Afrotyphlops schmidti was about in miombo woodland and in some cases, there was gallery halfway consumed, but the thickness of this prey item Specimens for mm. Broadley et al.

Additionally, Spawls et al. The holotype was kept in captivity for some time after capture, during Distribution. The far north as Burundi Broadley and Howell, ; Caro et al. The latter , but some populations e. Morphologically, the two species can usually be subfamily Aparallactinae Figueroa et al. As is the case with most species of aparallactines, coloration of P. This contrasts with the vibrant yellow or morphological conservatism is common within Polemon.

These species are obs. These records encompass a large geographic area black, white-edged ventrals, showed substantial genetic with multiple habitats in different elevations, and in some differentiation i. Its relationship ater, P. A based on a single male specimen from lowland rainforest in surprising result from the phylogenetic analyses of Portillo Poko Ituri rainforest , northeastern DRC.

This specimen has et al. Polemon christyi, P. Based on these features gabonensis, and P. The shape of the nasal and postocular P. De congeners de Witte and Laurent, Wagner et al. Other also recognized Polemon leopoldi as a distinct species. Several illustrations of de Witte, ; Broadley et al.

Within Lualaba, Haut- the head of a specimen of P. Polemon ater might have adapted to the miombo near the shore of Lake Tanganyika EG, pers. Although the park is dominated by farming management, uncontrolled fires, mining, and other grasslands and woodlands, it contains some gallery forest environmental degradation linked to human population Hillman Smith et al.

Six specimens of P. Because of these factors, these habitats are constant- reported by de Witte , from Virunga National ly at risk, especially unprotected regions in southeastern DRC Park included Mutsora savanna habitat, m and Indray miombo woodlands and savannas Sodhi et al. Additionally, southeastern relatively xeric habitats in the park. Mercurio recorded DRC is known to harbor high species diversity of plants, a specimen of P.

This specimen Greenbaum et al. Given the results herein and from Portillo et al. Possible popula- ; Chippaux, ; Mercurio, , but otherwise it has tions in Rwanda, Burundi, and Malawi require further study. Further genetic and morphological Given the proximity of the Dilolo locality Laurent, b examination of the Malawi population is needed to deter- to the border of DRC, P.

The montane forest records of P. Institutional abbreviations follow — m or P. We thus restrict the known range of P. Polemon christyi: BMNH These results also indicated that P.

Fieldwork by Z. Hughes, E. Angola; ZMB , Cameroon. Greenbaum, and M. We thank W. Portillo and E. It is with great sadness that we note that our William Roy Branch did not live to see the publication of this manuscript. His passing is a huge loss to the many colleagues who treasured his friendship, Polemon gabonensis: BMNH Phylogeography DRC.

Monographs — Behangana, M. Herpetological results of the Vernay Bulletin of the American Museum of Natural History — Polemon griseiceps: BMNH Descriptions of new snakes in the roon. The Annals and Magazine of Natural History — Boulenger, G. Bayon in Uganda. Bourgeois, M. Broadley, D. The reptiles and amphibians of Zambia. The Puku — Reed, M. Schmidt and G. The reptiles of ; E. Greenbaum, C. Kusamba, W. Aristote thank their field companions M.

Zigabe, Journal of Herpetology — Marcel, M. Luhumyo, J. Akuku, F. Alonda, and Broadley, D. Craig, and J. Snakes of the late A. The Centre de Recherche en Sciences Zambia. Chimaira, Frankfurt am Main, Germany.

A check list of the Dowling, H. A proposed standard system of reptiles of Tanzania, with synoptic keys. Syntarsus — British Journal of Herpetology Broadley, D. On a collection — Feakins, S. Global and Bredo. In: Southern Rhodesia Natural Sciences — Cenozoic Mammals of Africa.

Werdelin and W. Sanders Caro, T. Evans, E. Fitzherbert, T. Gardner, K. University of California Press, Oakland, California. Howell, R. Drewes, and H. Things heat up fast when they are both drugged. Smiley doesn't want to believe the sweet human would dose them with the breeding drug. He's willing to trust her and determined to save her life. He'll hold her.

Protect her. Offer up his body to distract them both from the pain. She is his female, even if she doesn't realize it yet.

Dana is visiting Homeland when she meets a New Species who tugs at her heartstrings. Candi lost the male she loved, but never forgot him. A human female claiming to have been reared at Mercile has demanded entry to Homeland.

Hero rushes to Medical and comes face-to-face with his past. Working together has forged a strong friendship between Melinda York and Mary Muller. He just wants to keep Mel safe. Mary is the brunt of jokes because of her extreme fear of animals.

Is she the only one who understands that? That would make her a crappy best friend, though. New Species. Book 1 in the New Species series. But loving Fury is one thing…taming him is another.

Book 2 in the New Species series. Book 3 in the New Species series. Book 4 in the New Species series. Book 5 in the New Species series. Book 6 in the New Species series. Book 7 in the New Species series. Book 8 in the New Species series. Book 9 in the New Species series. Book 10 in the New Species series. Book 11 in the New Species series. Book 12 in the New Species series. Book 13 in the New Species series. Book 14 in the New Species series. Book 15 in the New Species series.