The first ques,on we are interested in answering is- when did amphibians first appear?? Let s look at the fossil record to answer this ques,on.

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2 The first ques,on we are interested in answering is- when did amphibians first appear?? Let s look at the fossil record to answer this ques,on. Here we are looking at a geologic,me scale- with modern date at the top and 650 milion years ago at the boeom. And the interes,ng thing to note is that although the earth is billions of years old- we don t get out first fossil of living organisms un,l 650 million years ago. Palentologists have broken up the,me scale into periods that are divided by major events. For example- Dinosaurs become ex,nct at the Cretaceous- Paleogene boundary. If we try to look at the evolu,on of modern day animals- it starts in the Cambrian with the evolu,on of Fishes. Land plants evolved during the Silurian, and by the Devonian we get Amphibians at about 370 million years ago. And the organism that gave rise to modern amphibians is a creature known as Tikktalik. Here is the fossil- and this is a reconstruc,on of what the organism probably looked like. What s really spectacular is that this organism could prop itself up on it s front limbs- allowing its head to be above the water. Paleontologists speculate that Tikktalik could do this because there are lots of changes to the pelvic and pectoral girldes between this fossil and fishes of the,me. 2

3 So what are the modern day amphibians. We have 3 orders of amphibians. We will start at the top with the Order- Gymnophonia- which is a group of limbless amphibians. They are found mostly in the tropics, and live underground. This is a very understudied group because they are hard to observe and find. Next are the Caudata- which are newts and salamanders. The Appalachian mountains are a salamander hotspot- with about 90 species, which is really incredible. And finally we have Anura- our toads and frogs. There are approximately 7000 species of amphibians- compared to about 10,000 described bird species, and about 5,600 mammal species. And sadly, ~30% of amphibian species are threatened or are declining. Which is the highest for any vertebrate group. Compare this to 12% of bird species, and 23% of mammals. 3

4 Next, I d like to highlight a couple par,cularly sad frog ex,nc,ons. 1- This is the mouth brooding frog, Na,ve to Queensland Australia, There were only 2 known species in this Genus, and they became ex,nct in the mid- 1980s. The females of this species would incubate the prejuvenile stage in its stomach- which is accomplishes the same things as a bird si]ng on its eggs. No other frog species is known to do this. 2- The Costa Rican Golden Frog. Na,ve to Monteverde Costa Rica. And if you hear herpetologists talking about this species, they would tell you it was so hard to walk around the jungle in Monteverde, you couldbn t put your foot anywhere without stepping on them- It was last seen in And finally the Panamanian Golden Frog. The na,onal treasure and symbol of Panama. There were similar stories of high density in jungles throughout Central Panama- but this species was last seen in the wild in Biologists hypothesized that this species would be really suscep,ble to disease and were able to bring some into cap,vity before all of them died in the wild. They breed really well in zoos- and now there are a number of projects and programs trying to reintroduce them. 4

5 Now we ll talk about what is threatening amphibian popula,ons? The largest cause to declines is habitat loss- in the forms of destruc,on, modifica,on, and fragmenta,on of habitat. Here is a map of the worlds forests. Red areas show zones of deforesta,on. Dark green are areas of net gain forest, and lime green is current forest cover. No,ce that most red areas are concentrated in the tropics- where most of the world s biodiversity is concentrated. Most Amphibians need both aqua,c and terrestrial environments- and since they rely on both habitat types- they are more suscep,ble to declines and changes to the configura,on of the habitat. Habitat fragmenta,on is also a problem because patch isola,on can lead to inbreeding and gene,c dric. 5

6 A second threat is pollu,on. There are numerous reports of malnutri,on and malforma,on of amphibians. Pes,cides and herbicides are especially detrimental because they affect development of the embryo- which is likely laid in a pond- and they act like hormone mimics- leading to problems with the reproduc,ve system of amphibians. 6

7 And the third largest threat to amphibians is disease- par,cularly the Batrachochytrium dendroba1dis- which I will just call Bd It has been linked to over 350 species ex,nc,ons, and many more amphibian declines worldwide. I ll spend the remainder of the talk about the fungus. At the boeom of the page is a picture of a zoosporangium in the skin of an amphibian. 7

8 Well, first- what is it? Bd is an aqua,c fungus, the mo,le stage looks like sperm- as you can see at the top of the picture on the right- It has a single flagella it uses to move around during the mo,le stage. Once the zoospore finds a host- It starts encys,ng on the skin, and grow into a zoosporangium. The zoosporangium matures, and starts to replicate zoospores inside. Then it grows a discharge tube to the surface of the skin, and releases more zoospores to re- infect the host or others. Bd is one of the few funguses known to cause mass ex,nc,ons of vertebrates. Other examples include the White- nose fungus affec,ng Bats, and the new Batrachochytrium salamandrus fungus killing Fire salamanders in Europe. 8

9 So where is Bd? This is a map of the world- and the red pins are infected sites, white pins are exact locali,es of not infected sites, and blue pins are approximate locali,es of not infected sites. Bd has a global distribu,on and can be found on every con,nent amphibians are found on. Un,l recently the only place that con,nusously tested nega,ve was Madagascar- but that changed in January. Currenltly biologists are intensively surveying and trying to protect a lot of the endemic amphibian fauna. Another interes,ng thing to note about the map- is the lack of sampling in central Africa and Asia. Not too much is known about those amphibians or if Bd has caused large declines in those areas. 9

10 This is a picture of the Sierra Mountains and Rana muscosa- in 2005 when Bd first arrived in the loca,on. Amphibians have never interacted with a pathogen like it before- so many are suscep,ble. Many amphibians throughout tropical La,n America experience a similar reac,on. Devasta,ng declines happen within weeks of Bd arrival. And declines can be as high as 100%. 10

11 We ve spent all this,me talking about the incredible diversity of amphibians, how long they ve been around, and their sad demise as a group. There are several ways you can help out to STOP their decline and ex,nc,ons. 1. Don t use pes,cides. We talked about the harmful effects of pollu,on, and chemicals used in agriculture also pollute the environment by introducing harmful compounds. Most pesi,cides also act as hormone mimics making them even worse if you are an amphibian and come into contact with them- they can especially cause reproduc,on issues. 2. Don t purchase wild caught amphibians. Some pet traders go to Developing countries and capture amphibians to sell- they deplete local popula,ons, impact the local tourism industry, and can cause ecosystem imbalances. 3. Don t release amphibians purchased in pet stores into the wild. These amphibians have been exposed to a number of pathogens in the loca,ons they have been housed- and if you release the amphibian into the environment, you are also releasing the associated pathogens on it. 4. Reduce, reuse, recycle- This helps cut back on habitat loss. Less material, less waste, less pollu,on. 5. Watch what you eat Try to eat organic- support people that don t use pes,cides. Reduce pollu,on. Buy local- reduce the amount of fossil fuels devoted to transporta,on. Be aware of the habitat loss that agriculture fosters- try to support small 11

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