All of them.
Now, That's a pretty bold statement to start an answer off with so let me hit you with a few facts first and then I'll get onto what the future, potentially, holds. Humanity has wiped out 60% of mammals, birds, fish and reptiles since 1970. Think about that. In 50 years we have managed to destroy billions of years worth of evolution. Another recent study found that man has been responsible for the extinction of 83% of all mammals that have ever walked the face of the earth and around 50% of all plant life. Sad thing is that this cycle of destruction is far from over,in fact it is increasing exponentially as mans ever growing need for accommodation, food and other resources grows and grows.
More than 50% of the worlds oceans are now being industrially fished, creating a catastrophic effect on the worlds sea life population. Over 1 million seabirds and around 100, 000 sea animals are killed by pollution through oil spillages, exposure to human waste in addition to this. Further to this pollution damages coral reefs through bleaching and we are in danger of losing some of the worlds most iconic underwater features such as the great barrier reef. Reefs are destroyed when trawler nets are dragged along the ocean floor. These reefs provide a home to literally thousands of species and sub species of sea life, many or all of whom could face extinction if changes are not made.
Over 3/4 of the land in the world is now being affected by human populace and year on the the number grows. More than a third of the worlds land space is now taken over by farming and the livestock industry is one of the largest sources of greenhouse gasses.and has a massive effect on biodiversity through the destruction of natural habitats and green belt land. The gobal average amount of water needed to produce 1 pound of beef (that's just under a half kilo for all you metric folks) is nearly 1,800 litres! Livestock farming is reported to be responsible for 37% and 65% of global methane and nitrous oxide emissions.
These, unfortunately, are just the tip of the iceberg of factors of why we are heading for what many scientists believe will be the 6th global extinction and the very first one to be created, largely, by a single species. Us. It is vital that the message is spread and that we all start to take action to help to prevent this. Consume less or no meat, recycle where you can, avoid buying products in unnecessary packaging, avoid using disposable clothes shops and repair or reuse your clothing and equipment as much as possible, turn of lights and electricity where possible, chose a renewable energy supplier...the list goes on and on and, whilst it might seem daunting, you can start by making one change at a time, one per month and introduce them slowly. I certainly dont want to look into the eyes of my children and explain to them why we have left them an impossible environmental catastrophe to deal with and, worse, why I did nothing about it.
Those people that were out marching in the streets recently to raise awareness of climate change, they weren't just crazy hippies and bleeding heart liberals. In fact, I hope that reading this you might consider going to join them. Climate change wot just stop. Its a fact and there is no point in burying your head in the sand and hoping it goes away. If you want to prevent the destruction of many or even all species on the planet the time to act is now.